Fix __builtin_nested_func_ptr_{created,deleted} symbol versions [PR113402]

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>