The symbols for the functions supporting heap-based trampolines were
exported at an incorrect symbol version, the following patch fixes that.

As requested in the PR, this also renames __builtin_nested_func_ptr* to
__gcc_nested_func_ptr*.  In carrying our the rename, we move the builtins
to use DEF_EXT_LIB_BUILTIN.

	PR libgcc/113402

gcc/ChangeLog:

	* builtins.cc (expand_builtin): Handle BUILT_IN_GCC_NESTED_PTR_CREATED
	and BUILT_IN_GCC_NESTED_PTR_DELETED.
	* builtins.def (BUILT_IN_GCC_NESTED_PTR_CREATED,
	BUILT_IN_GCC_NESTED_PTR_DELETED): Make these builtins LIB-EXT and
	rename the library fallbacks to __gcc_nested_func_ptr_created and
	__gcc_nested_func_ptr_deleted.
	* doc/invoke.texi: Rename these to __gcc_nested_func_ptr_created
	and __gcc_nested_func_ptr_deleted.
	* tree-nested.cc (finalize_nesting_tree_1): Use builtin_explicit for
	BUILT_IN_GCC_NESTED_PTR_CREATED and BUILT_IN_GCC_NESTED_PTR_DELETED.
	* tree.cc (build_common_builtin_nodes): Build the
	BUILT_IN_GCC_NESTED_PTR_CREATED and BUILT_IN_GCC_NESTED_PTR_DELETED local
	builtins only for non-explicit.

libgcc/ChangeLog:

	* config/aarch64/heap-trampoline.c: Rename
	__builtin_nested_func_ptr_created to __gcc_nested_func_ptr_created and
	__builtin_nested_func_ptr_deleted to __gcc_nested_func_ptr_deleted.
	* config/i386/heap-trampoline.c: Likewise.
	* libgcc2.h: Likewise.
	* libgcc-std.ver.in (GCC_7.0.0): Likewise and then move
	__gcc_nested_func_ptr_created and
	__gcc_nested_func_ptr_deleted from this symbol version to ...
	(GCC_14.0.0): ... this one.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
Co-authored-by: Jakub Jelinek <jakub@redhat.com>

This patch adds the strub attribute for function and variable types,
command-line options, passes and adjustments to implement it,
documentation, and tests.

Stack scrubbing is implemented in a machine-independent way: functions
with strub enabled are modified so that they take an extra stack
watermark argument, that they update with their stack use, and the
caller can then zero it out once it regains control, whether by return
or exception.  There are two ways to go about it: at-calls, that
modifies the visible interface (signature) of the function, and
internal, in which the body is moved to a clone, the clone undergoes
the interface change, and the function becomes a wrapper, preserving
its original interface, that calls the clone and then clears the stack
used by it.

Variables can also be annotated with the strub attribute, so that
functions that read from them get stack scrubbing enabled implicitly,
whether at-calls, for functions only usable within a translation unit,
or internal, for functions whose interfaces must not be modified.

There is a strict mode, in which functions that have their stack
scrubbed can only call other functions with stack-scrubbing
interfaces, or those explicitly marked as callable from strub
contexts, so that an entire call chain gets scrubbing, at once or
piecemeal depending on optimization levels.  In the default mode,
relaxed, this requirement is not enforced by the compiler.

The implementation adds two IPA passes, one that assigns strub modes
early on, another that modifies interfaces and adds calls to the
builtins that jointly implement stack scrubbing.  Another builtin,
that obtains the stack pointer, is added for use in the implementation
of the builtins, whether expanded inline or called in libgcc.

There are new command-line options to change operation modes and to
force the feature disabled; it is enabled by default, but it has no
effect and is implicitly disabled if the strub attribute is never
used.  There are also options meant to use for testing the feature,
enabling different strubbing modes for all (viable) functions.


for  gcc/ChangeLog

	* Makefile.in (OBJS): Add ipa-strub.o.
	(GTFILES): Add ipa-strub.cc.
	* builtins.def (BUILT_IN_STACK_ADDRESS): New.
	(BUILT_IN___STRUB_ENTER): New.
	(BUILT_IN___STRUB_UPDATE): New.
	(BUILT_IN___STRUB_LEAVE): New.
	* builtins.cc: Include ipa-strub.h.
	(STACK_STOPS, STACK_UNSIGNED): Define.
	(expand_builtin_stack_address): New.
	(expand_builtin_strub_enter): New.
	(expand_builtin_strub_update): New.
	(expand_builtin_strub_leave): New.
	(expand_builtin): Call them.
	* common.opt (fstrub=*): New options.
	* doc/extend.texi (strub): New type attribute.
	(__builtin_stack_address): New function.
	(Stack Scrubbing): New section.
	* doc/invoke.texi (-fstrub=*): New options.
	(-fdump-ipa-*): New passes.
	* gengtype-lex.l: Ignore multi-line pp-directives.
	* ipa-inline.cc: Include ipa-strub.h.
	(can_inline_edge_p): Test strub_inlinable_to_p.
	* ipa-split.cc: Include ipa-strub.h.
	(execute_split_functions): Test strub_splittable_p.
	* ipa-strub.cc, ipa-strub.h: New.
	* passes.def: Add strub_mode and strub passes.
	* tree-cfg.cc (gimple_verify_flow_info): Note on debug stmts.
	* tree-pass.h (make_pass_ipa_strub_mode): Declare.
	(make_pass_ipa_strub): Declare.
	(make_pass_ipa_function_and_variable_visibility): Fix
	formatting.
	* tree-ssa-ccp.cc (optimize_stack_restore): Keep restores
	before strub leave.
	* attribs.cc: Include ipa-strub.h.
	(decl_attributes): Support applying attributes to function
	type, rather than pointer type, at handler's request.
	(comp_type_attributes): Combine strub_comptypes and target
	comp_type results.
	* doc/tm.texi.in (TARGET_STRUB_USE_DYNAMIC_ARRAY): New.
	(TARGET_STRUB_MAY_USE_MEMSET): New.
	* doc/tm.texi: Rebuilt.
	* cgraph.h (symtab_node::reset): Add preserve_comdat_group
	param, with a default.
	* cgraphunit.cc (symtab_node::reset): Use it.

for  gcc/c-family/ChangeLog

	* c-attribs.cc: Include ipa-strub.h.
	(handle_strub_attribute): New.
	(c_common_attribute_table): Add strub.

for  gcc/ada/ChangeLog

	* gcc-interface/trans.cc: Include ipa-strub.h.
	(gigi): Make internal decls for targets of compiler-generated
	calls strub-callable too.
	(build_raise_check): Likewise.
	* gcc-interface/utils.cc: Include ipa-strub.h.
	(handle_strub_attribute): New.
	(gnat_internal_attribute_table): Add strub.

for  gcc/testsuite/ChangeLog

	* c-c++-common/strub-O0.c: New.
	* c-c++-common/strub-O1.c: New.
	* c-c++-common/strub-O2.c: New.
	* c-c++-common/strub-O2fni.c: New.
	* c-c++-common/strub-O3.c: New.
	* c-c++-common/strub-O3fni.c: New.
	* c-c++-common/strub-Og.c: New.
	* c-c++-common/strub-Os.c: New.
	* c-c++-common/strub-all1.c: New.
	* c-c++-common/strub-all2.c: New.
	* c-c++-common/strub-apply1.c: New.
	* c-c++-common/strub-apply2.c: New.
	* c-c++-common/strub-apply3.c: New.
	* c-c++-common/strub-apply4.c: New.
	* c-c++-common/strub-at-calls1.c: New.
	* c-c++-common/strub-at-calls2.c: New.
	* c-c++-common/strub-defer-O1.c: New.
	* c-c++-common/strub-defer-O2.c: New.
	* c-c++-common/strub-defer-O3.c: New.
	* c-c++-common/strub-defer-Os.c: New.
	* c-c++-common/strub-internal1.c: New.
	* c-c++-common/strub-internal2.c: New.
	* c-c++-common/strub-parms1.c: New.
	* c-c++-common/strub-parms2.c: New.
	* c-c++-common/strub-parms3.c: New.
	* c-c++-common/strub-relaxed1.c: New.
	* c-c++-common/strub-relaxed2.c: New.
	* c-c++-common/strub-short-O0-exc.c: New.
	* c-c++-common/strub-short-O0.c: New.
	* c-c++-common/strub-short-O1.c: New.
	* c-c++-common/strub-short-O2.c: New.
	* c-c++-common/strub-short-O3.c: New.
	* c-c++-common/strub-short-Os.c: New.
	* c-c++-common/strub-strict1.c: New.
	* c-c++-common/strub-strict2.c: New.
	* c-c++-common/strub-tail-O1.c: New.
	* c-c++-common/strub-tail-O2.c: New.
	* c-c++-common/torture/strub-callable1.c: New.
	* c-c++-common/torture/strub-callable2.c: New.
	* c-c++-common/torture/strub-const1.c: New.
	* c-c++-common/torture/strub-const2.c: New.
	* c-c++-common/torture/strub-const3.c: New.
	* c-c++-common/torture/strub-const4.c: New.
	* c-c++-common/torture/strub-data1.c: New.
	* c-c++-common/torture/strub-data2.c: New.
	* c-c++-common/torture/strub-data3.c: New.
	* c-c++-common/torture/strub-data4.c: New.
	* c-c++-common/torture/strub-data5.c: New.
	* c-c++-common/torture/strub-indcall1.c: New.
	* c-c++-common/torture/strub-indcall2.c: New.
	* c-c++-common/torture/strub-indcall3.c: New.
	* c-c++-common/torture/strub-inlinable1.c: New.
	* c-c++-common/torture/strub-inlinable2.c: New.
	* c-c++-common/torture/strub-ptrfn1.c: New.
	* c-c++-common/torture/strub-ptrfn2.c: New.
	* c-c++-common/torture/strub-ptrfn3.c: New.
	* c-c++-common/torture/strub-ptrfn4.c: New.
	* c-c++-common/torture/strub-pure1.c: New.
	* c-c++-common/torture/strub-pure2.c: New.
	* c-c++-common/torture/strub-pure3.c: New.
	* c-c++-common/torture/strub-pure4.c: New.
	* c-c++-common/torture/strub-run1.c: New.
	* c-c++-common/torture/strub-run2.c: New.
	* c-c++-common/torture/strub-run3.c: New.
	* c-c++-common/torture/strub-run4.c: New.
	* c-c++-common/torture/strub-run4c.c: New.
	* c-c++-common/torture/strub-run4d.c: New.
	* c-c++-common/torture/strub-run4i.c: New.
	* g++.dg/strub-run1.C: New.
	* g++.dg/torture/strub-init1.C: New.
	* g++.dg/torture/strub-init2.C: New.
	* g++.dg/torture/strub-init3.C: New.
	* gnat.dg/strub_attr.adb, gnat.dg/strub_attr.ads: New.
	* gnat.dg/strub_ind.adb, gnat.dg/strub_ind.ads: New.

for  libgcc/ChangeLog

	* Makefile.in (LIB2ADD): Add strub.c.
	* libgcc2.h (__strub_enter, __strub_update, __strub_leave):
	Declare.
	* strub.c: New.
	* libgcc-std.ver.in (__strub_enter): Add to GCC_14.0.0.
	(__strub_update, __strub_leave): Likewise.

The libgcc-exported runtime component of control flow redundancy
hardening was missing symbol versioning information.  Add it.


for  libgcc/ChangeLog

	* libgcc-std.ver.in (__hardcfr_check): Add to GCC_14.0.0.

Add support for heap-based trampolines on x86_64-linux, aarch64-linux,
and x86_64-darwin. Implement the __builtin_nested_func_ptr_created and
__builtin_nested_func_ptr_deleted functions for these targets.

Co-Authored-By: Maxim Blinov <maxim.blinov@embecosm.com>
Co-Authored-By: Iain Sandoe <iain@sandoe.co.uk>
Co-Authored-By: Francois-Xavier Coudert <fxcoudert@gcc.gnu.org>

libgcc/ChangeLog:

	* libgcc2.h (__builtin_nested_func_ptr_created): Declare.
	(__builtin_nested_func_ptr_deleted): Declare.
	* libgcc-std.ver.in: Add the new symbols.
	* config/aarch64/heap-trampoline.c: Implement heap-based
	trampolines for aarch64.
	* config/aarch64/t-heap-trampoline: Add rule to build
	config/aarch64/heap-trampoline.c
	* config/i386/heap-trampoline.c: Implement heap-based
	trampolines for x86_64.
	* config/i386/t-heap-trampoline: Add rule to build
	config/i386/heap-trampoline.cc
	* config.host: Handle --enable-heap-trampolines on
	x86_64-*-linux*, aarch64-*-linux*, x86_64-*-darwin*.

This patch adds the library helpers for multiplication, division + modulo
and casts from and to floating point (both binary and decimal).
As described in the intro, the first step is try to reduce further the
passed in precision by skipping over most significant limbs with just zeros
or sign bit copies.  For multiplication and division I've implemented
a simple algorithm, using something smarter like Karatsuba or Toom N-Way
might be faster for very large _BitInts (which we don't support right now
anyway), but could mean more code in libgcc, which maybe isn't what people
are willing to accept.
For the to/from floating point conversions the patch uses soft-fp, because
it already has tons of handy macros which can be used for that.  In theory
it could be implemented using {,unsigned} long long or {,unsigned} __int128
to/from floating point conversions with some frexp before/after, but at that
point we already need to force it into integer registers and analyze it
anyway.  Plus, for 32-bit arches there is no __int128 that could be used
for XF/TF mode stuff.
I know that soft-fp is owned by glibc and I think the op-common.h change
should be propagated there, but the bitint stuff is really GCC specific
and IMHO doesn't belong into the glibc copy.

2023-09-06  Jakub Jelinek  <jakub@redhat.com>

	PR c/102989
libgcc/
	* config/aarch64/t-softfp (softfp_extras): Use += rather than :=.
	* config/i386/64/t-softfp (softfp_extras): Likewise.
	* config/i386/libgcc-glibc.ver (GCC_14.0.0): Export _BitInt support
	routines.
	* config/i386/t-softfp (softfp_extras): Add fixxfbitint and
	bf, hf and xf mode floatbitint.
	(CFLAGS-floatbitintbf.c, CFLAGS-floatbitinthf.c): Add -msse2.
	* config/riscv/t-softfp32 (softfp_extras): Use += rather than :=.
	* config/rs6000/t-e500v1-fp (softfp_extras): Likewise.
	* config/rs6000/t-e500v2-fp (softfp_extras): Likewise.
	* config/t-softfp (softfp_floatbitint_funcs): New.
	(softfp_bid_list): New.
	(softfp_func_list): Add sf and df mode from and to _BitInt libcalls.
	(softfp_bid_file_list): New.
	(LIB2ADD_ST): Add $(softfp_bid_file_list).
	* config/t-softfp-sfdftf (softfp_extras): Add fixtfbitint and
	floatbitinttf.
	* config/t-softfp-tf (softfp_extras): Likewise.
	* libgcc2.c (bitint_reduce_prec): New inline function.
	(BITINT_INC, BITINT_END): Define.
	(bitint_mul_1, bitint_addmul_1): New helper functions.
	(__mulbitint3): New function.
	(bitint_negate, bitint_submul_1): New helper functions.
	(__divmodbitint4): New function.
	* libgcc2.h (LIBGCC2_UNITS_PER_WORD): When building _BitInt support
	libcalls, redefine depending on __LIBGCC_BITINT_LIMB_WIDTH__.
	(__mulbitint3, __divmodbitint4): Declare.
	* libgcc-std.ver.in (GCC_14.0.0): Export _BitInt support routines.
	* Makefile.in (lib2funcs): Add _mulbitint3.
	(LIB2_DIVMOD_FUNCS): Add _divmodbitint4.
	* soft-fp/bitint.h: New file.
	* soft-fp/fixdfbitint.c: New file.
	* soft-fp/fixsfbitint.c: New file.
	* soft-fp/fixtfbitint.c: New file.
	* soft-fp/fixxfbitint.c: New file.
	* soft-fp/floatbitintbf.c: New file.
	* soft-fp/floatbitintdf.c: New file.
	* soft-fp/floatbitinthf.c: New file.
	* soft-fp/floatbitintsf.c: New file.
	* soft-fp/floatbitinttf.c: New file.
	* soft-fp/floatbitintxf.c: New file.
	* soft-fp/op-common.h (_FP_FROM_INT): Add support for rsize up to
	4 * _FP_W_TYPE_SIZE rather than just 2 * _FP_W_TYPE_SIZE.
	* soft-fp/bitintpow10.c: New file.
	* soft-fp/fixsdbitint.c: New file.
	* soft-fp/fixddbitint.c: New file.
	* soft-fp/fixtdbitint.c: New file.
	* soft-fp/floatbitintsd.c: New file.
	* soft-fp/floatbitintdd.c: New file.
	* soft-fp/floatbitinttd.c: New file.

From-SVN: r279813

From-SVN: r267494

From-SVN: r256169

From-SVN: r243994

	* Makefile.in (LIB2_DIVMOD_FUNCS): Add _divmoddi4.
	* libgcc2.c (__divmoddi4): New function.
	* libgcc2.h (__divmoddi4): Declare.
	* libgcc-std.ver.in (GCC_7.0.0): New. Add __PFX_divmoddi4
	and __PFX_divmodti4.

From-SVN: r241804

From-SVN: r232055

From-SVN: r219188

From-SVN: r206295

From-SVN: r195731

	PR bootstrap/55370
	* libgcc-std.ver.in: Add GCC_4.8.0 and %inherit for it.

From-SVN: r193648

	* generic-morestack.c (__splitstack_find): Check for NULL old
	stack value.
	(__splitstack_resetcontext): New function.
	(__splitstack_releasecontext): New function.
	* libgcc-std.ver.in: Add new functions to GCC_4.7.0.

From-SVN: r181771

libgcc/:
	* generic-morestack.c: Include <string.h>.
	(uintptr_type): Define.
	(struct initial_sp): Add dont_block_signals field.  Reduce size of
	extra array by 1.
	(allocate_segment): Set prev field to NULL.  Don't set
	__morestack_current_segment or __morestack_segments.
	(__generic_morestack): Update current->prev and *pp after calling
	allocate_segment.
	(__morestack_block_signals): Don't do anything if
	dont_block_signals is set.
	(__morestack_unblock_signals): Likewise.
	(__generic_findstack): Check for initial_sp == NULL.  Add casts to
	uintptr_type.
	(__splitstack_block_signals): New function.
	(enum __splitstack_content_offsets): Define.
	(__splitstack_getcontext, __splitstack_setcontext): New functions.
	(__splitstack_makecontext): New function.
	(__splitstack_block_signals_context): New function.
	(__splitstack_find_context): New function.
	* config/i386/morestack.S (__morestack_get_guard): New function.
	(__morestack_set_guard, __morestack_make_guard): New functions.
	* libgcc-std.ver.in: Add new functions to GCC_4.7.0.

gcc/testsuite/:
	* lib/target-supports.exp (check_effective_target_ucontext_h): New
	procedure.
	* gcc.dg/split-5.c: New test.

From-SVN: r181234

	libgcc/
	* Makefile.in (LIBGCC_VER_FIXEDPOINT_GNU_PREFIX): New.
	(libgcc-std.ver.in): Use above.
	* fixed-bit.h (LIBGCC2_FIXEDBIT_GNU_PREFIX): Define, if
	LIBGCC2_GNU_PREFIX is defined.  Use instead of LIBGCC2_GNU_PREFIX
	throughout file.
	* config/t-fixedpoint-gnu-prefix: New file.
	* config/t-gnu-prefix (LIBGCC_VER_FIXEDPOINT_GNU_PREFIX): Set.
	* libgcc-std.ver.in (fixed-point routines): Use __FIXPTPFX__
	instead of __PFX__.

From-SVN: r177019

	libgcc/
	* Makefile.in (lib2funcs): Add _clrsbsi2 and _clrsbdi2.
	* libgcc-std.ver.in (GCC_4.7.0): New section.

	gcc/
	* doc/extend.texi (__builtin_clrsb, __builtin_clrsbl,
	__builtin_clrsbll): Document.
	* doc/rtl.texi (clrsb): New entry.
	* optabs.c (widen_leading): Renamed from widen_clz.  New argument
	UNOPTAB.  All callers changed.  Use UNOPTAB instead of clz_optab.
	(expand_unop): Handle clrsb_optab.
	(init_optabs): Initialize it.
	* optabs.h (enum optab_index): New entry OTI_clrsb.
	(clrsb_optab): Define.
	* genopinit.c (optabs): Add an entry for it.
	* builtins.c (expand_builtin): Handle clrsb builtin functions.
	* builtins.def (BUILT_IN_CLRSB, BUILT_IN_CLRSBIMAX, BUILT_IN_CLRSBL,
	BUILT_IN_CLRSBLL): New.
	* rtl.def (CLRSB): New code.
	* dwarf2out.c (mem_loc_descriptor): Handle it.
	* simplify-rtx.c (simplify_const_unary_operation): Likewise.
	Use op_mode rather than mode when optimizing ffs, clz, ctz, parity
	and popcount.
	* libgcc2.c (__clrsbSI2, __clrsbDI2): New functions.
	* libgcc2.h (__clrsbSI2, __clrsbDI2): Define and declare.
	(__ctzDI2): Move declaration.
	* config/bfin/bfin.md (clrsbsi2): New expander.
	(signbitssi2): Use the CLRSB rtx.
	(clrsbhi2): Renamed from signbitshi2.  Use the CLRSB rtx.
	* config/bfin/bfin.c (bdesc_1arg): Changed accordingly.

	gcc/testsuite/
	* gcc.c-torture/excute/builtin-bitops-1.c (MAKE_FUNS): Make
	my_clrsb test functions.
	(main): Test clrsb.
	* gcc.dg/builtin-protos-1.c (test_s, test_u, test_sl, test_ul,
	test_sll, test_ull): Add clrsb tests.
	* gcc.dg/torture/builtin-attr-1.c: Add tests for clrsb, clrsbl,
	clrsbll.

From-SVN: r175261

	gcc/
	* libgcc2.h (__NW, __NDW): Define using a __gnu_ prefix if
	LIBGCC2_GNU_PREFIX is defined.
	(__N): New macro.
	(__powisf2, __powidf2, __powitf2, __powixf2, __bswapsi2, __bswapdi2,
	__mulsc3, __muldc3, __mulxc3, __multc3, __divsc3, __divdc3, __divxc3,
	__divtc3, __udiv_w_sdiv, __clear_cache, __enable_execute_stack,
	__clz_tab): Define using __N.
	(__absvsi2, __negvsi2, __addvsi3, __subvsi3, __mulvsi3): Likewise if
	COMPAT_SIMODE_TRAPPING_ARITHMETIC.
	* target.def (libfunc_gnu_prefix): New hook.
	* doc/tm.texi.in (LIBGCC2_GNU_PREFIX): Document.
	(TARGET_LIBFUNC_GNU_PREFIX): Add hook.
	* doc/tm.texi: Regenerate.
	* system.h (LIBGCC2_GNU_PREFIX): Poison.
	* optabs.c (gen_libfunc): Take the libfunc_gnu_prefix hook into
	account.
	(gen_interclass_conv_libfunc, gen_intraclass_conv_libfunc): Likewise.
	(init_optabs): Likewise for the bswap libfuncs.
	* tree.c (build_common_builtin_nodes): Likewise for complex multiply
	and divide.
	* config/t-slibgcc-elf-ver (SHLIB_MAPFILES): Use $$(libgcc_objdir).
	* config/t-slibgcc-sld (SHLIB_MAPFILES): Likewise.
	* libgcc-std.ver: Remove.
	* Makefile.in (srcdirify): Handle $$(libgcc_objdir).
	* config/frv/t-linux (SHLIB_MAPFILES): Use $$(libgcc_objdir) for
	libgcc-std.ver.
	* config/i386/t-linux (SHLIB_MAPFILES): Likewise.
	* config/mips/t-slibgcc-irix (SHLIB_MAPFILES): Likewise.
	* config/rs6000/t-aix43 (SHLIB_MAPFILES): Likewise.
	* config/rs6000/t-aix52 (SHLIB_MAPFILES): Likewise.
	* config/sparc/t-linux (SHLIB_MAPFILES): Likewise.
	* config/i386/t-linux (SHLIB_MAPFILES): Likewise.
	* config/i386/t-linux (SHLIB_MAPFILES): Likewise.
	* config/fixed-bit.h (FIXED_OP): Define differently depending on
	LIBGCC2_GNU_PREFIX. All uses changed not to pass leading underscores.
	(FIXED_CONVERT_OP, FIXED_CONVERT_OP2): Likewise.

	libgcc/
	* libgcc-std.ver.in: New file.
	* Makefile.in (LIBGCC_VER_GNU_PREFIX, LIBGCC_VER_SYMBOLS_PREFIX): New
	variables.
	(libgcc-std.ver): New rule.
	* config/t-gnu-prefix: New file.

From-SVN: r174187