nvptx: '#define MAX_FIXED_MODE_SIZE 128'

... instead of 64 via 'gcc/defaults.h':

    MAX_FIXED_MODE_SIZE GET_MODE_BITSIZE (DImode)

This fixes ICEs:

    [-FAIL: c-c++-common/pr111309-1.c  -Wc++-compat  (internal compiler error: in expand_fn_using_insn, at internal-fn.cc:268)-]
    [-FAIL:-]{+PASS:+} c-c++-common/pr111309-1.c  -Wc++-compat  (test for excess errors)
    [-UNRESOLVED:-]{+PASS:+} c-c++-common/pr111309-1.c  -Wc++-compat  [-compilation failed to produce executable-]{+execution test+}

    [-FAIL: c-c++-common/pr111309-1.c  -std=gnu++17 (internal compiler error: in expand_fn_using_insn, at internal-fn.cc:268)-]
    [-FAIL:-]{+PASS:+} c-c++-common/pr111309-1.c  -std=gnu++17 (test for excess errors)
    [-UNRESOLVED:-]{+PASS:+} c-c++-common/pr111309-1.c  -std=gnu++17 [-compilation failed to produce executable-]{+execution test+}
    [-FAIL: c-c++-common/pr111309-1.c  -std=gnu++26 (internal compiler error: in expand_fn_using_insn, at internal-fn.cc:268)-]
    [-FAIL:-]{+PASS:+} c-c++-common/pr111309-1.c  -std=gnu++26 (test for excess errors)
    [-UNRESOLVED:-]{+PASS:+} c-c++-common/pr111309-1.c  -std=gnu++26 [-compilation failed to produce executable-]{+execution test+}
    [-FAIL: c-c++-common/pr111309-1.c  -std=gnu++98 (internal compiler error: in expand_fn_using_insn, at internal-fn.cc:268)-]
    [-FAIL:-]{+PASS:+} c-c++-common/pr111309-1.c  -std=gnu++98 (test for excess errors)
    [-UNRESOLVED:-]{+PASS:+} c-c++-common/pr111309-1.c  -std=gnu++98 [-compilation failed to produce executable-]{+execution test+}

    [-FAIL: gcc.dg/torture/pr116480-1.c   -O0  (internal compiler error: in expand_fn_using_insn, at internal-fn.cc:268)-]
    [-FAIL:-]{+PASS:+} gcc.dg/torture/pr116480-1.c   -O0  (test for excess errors)
    [-FAIL: gcc.dg/torture/pr116480-1.c   -O1  (internal compiler error: in expand_fn_using_insn, at internal-fn.cc:268)-]
    [-FAIL:-]{+PASS:+} gcc.dg/torture/pr116480-1.c   -O1  (test for excess errors)
    PASS: gcc.dg/torture/pr116480-1.c   -O2  (test for excess errors)
    PASS: gcc.dg/torture/pr116480-1.c   -O3 -g  (test for excess errors)
    PASS: gcc.dg/torture/pr116480-1.c   -Os  (test for excess errors)

..., where we ran into 'gcc_assert (icode != CODE_FOR_nothing);' in
'gcc/internal-fn.cc:expand_fn_using_insn' for '__int128' '__builtin_clzg' etc.:

    during RTL pass: expand
    [...]/c-c++-common/pr111309-1.c: In function 'clzI':
    [...]/c-c++-common/pr111309-1.c:69:10: internal compiler error: in expand_fn_using_insn, at internal-fn.cc:268
    0x120ec2cf internal_error(char const*, ...)
            [...]/gcc/diagnostic-global-context.cc:517
    0x102c7c5b fancy_abort(char const*, int, char const*)
            [...]/gcc/diagnostic.cc:1722
    0x109708eb expand_fn_using_insn
            [...]/gcc/internal-fn.cc:268
    0x1098114f expand_internal_call(internal_fn, gcall*)
            [...]/gcc/internal-fn.cc:5273
    0x1098114f expand_internal_call(gcall*)
            [...]/gcc/internal-fn.cc:5281
    0x10594fc7 expand_call_stmt
            [...]/gcc/cfgexpand.cc:3049
    [...]

Likewise, as of commit e8ad697a
"libstdc++: Use new type-generic built-ins in <bit> [PR118855]",
the libstdc++ target library build ICEd in the same way.

Additionally, this change fixes:

    [-FAIL:-]{+PASS:+} gcc.dg/pr105094.c (test for excess errors)

..., which was:

    [...]/gcc.dg/pr105094.c: In function 'foo':
    [...]/gcc.dg/pr105094.c:11:12: error: size of variable 's' is too large

And, finally, regarding 'gcc.target/nvptx/stack_frame-1.c'.  Before, in
'gcc/cfgexpand.cc': 'expand_used_vars' -> 'expand_used_vars_for_block' ->
'expand_one_var' for 'ww' -> 'gcc/function.cc:use_register_for_decl' due to
'DECL_MODE (decl) == BLKmode' did 'return false;', thus -> 'add_stack_var'
(even if 'ww' wasn't then actually living on the stack).  Now, 'ww' has
'TImode' and 'use_register_for_decl' does 'return true;', thus ->
'expand_one_register_var', and therefore no unused stack frame emitted.

	gcc/
	* config/nvptx/nvptx.h (MAX_FIXED_MODE_SIZE): '#define'.
	gcc/testsuite/
	* gcc.target/nvptx/stack_frame-1.c: Adjust.