fmv: c++: Add check_target_clone hook for filtering target_clone versions.

fmv: c++: Add check_target_clone hook for filtering target_clone versions.

This patch introduces the TARGET_CHECK_TARGET_CLONE_VERSION hook
which is used to determine if a target_clones version string parses.

The hook has a flag to enable emitting diagnostics.

This is as specified in the Arm C Language Extension. The purpose of this
is to be able to ignore invalid versions to allow some portability of code
using target_clones attributes.

Currently this is only properly implemented for the Aarch64 backend.

For riscv which is the only other backend which uses target_version
semantics a partial implementation is present, where this hook is used
to check parsing, in which errors will be emitted on a failed parse
rather than warnings. A refactor of the riscv parsing logic would be
required to enable this functionality fully.

This fixes PR 118339 where parse failures could cause ICE in Aarch64.

gcc/ChangeLog:

	PR target/118339
	* target.def: Add check_target_clone_version hook.
	* tree.cc (get_clone_attr_versions): Add filter argument.
	(get_clone_versions): Add filter argument.
	* tree.h (get_clone_attr_versions): Add filter.
	(get_clone_versions): Add filter argument.
	* config/aarch64/aarch64.cc (aarch64_check_target_clone_version):
	New function
	(TARGET_CHECK_TARGET_CLONE_VERSION): New define.
	* config/riscv/riscv.cc (riscv_check_target_clone_version):
	New function.
	(TARGET_CHECK_TARGET_CLONE_VERSION): New define.
	* doc/tm.texi: Regenerated.
	* doc/tm.texi.in: Add documentation for new hook.
	* hooks.h (hook_stringslice_locationtptr_true): New function.
	* hooks.cc (hook_stringslice_locationtptr_true): New function.

gcc/c-family/ChangeLog:

	* c-attribs.cc (handle_target_clones_attribute): Update to use new hook.