Add warning for non-spec compliant FMV in Aarch64

This patch adds a warning when FMV is used for Aarch64.

The reasoning for this is the ACLE [1] spec for FMV has diverged
significantly from the current implementation and we want to prevent
potential future compatability issues.

There is a patch for an ACLE compliant version of target_version and
target_clone in progress but it won't make gcc-15.

This has been bootstrap and regression tested for Aarch64.
Is this okay for master and packport to gcc-14?

[1] https://github.com/ARM-software/acle/blob/main/main/acle.md#function-multi-versioning

gcc/ChangeLog:

	* config/aarch64/aarch64.cc
	(aarch64_process_target_version_attr): Add experimental warning.
	* config/aarch64/aarch64.opt: Add command line option to disable
	warning.
	* doc/invoke.texi: Add documentation for -W[no-]experimental-fmv-target.

gcc/testsuite/ChangeLog:

	* g++.target/aarch64/mv-1.C: Add CLI flag.
	* g++.target/aarch64/mv-symbols1.C: Add CLI flag.
	* g++.target/aarch64/mv-symbols2.C: Add CLI flag.
	* g++.target/aarch64/mv-symbols3.C: Add CLI flag.
	* g++.target/aarch64/mv-symbols4.C: Add CLI flag.
	* g++.target/aarch64/mv-symbols5.C: Add CLI flag.
	* g++.target/aarch64/mv-warning1.C: New test.
	* g++.target/aarch64/mvc-symbols1.C: Add CLI flag.
	* g++.target/aarch64/mvc-symbols2.C: Add CLI flag.
	* g++.target/aarch64/mvc-symbols3.C: Add CLI flag.
	* g++.target/aarch64/mvc-symbols4.C: Add CLI flag.
	* g++.target/aarch64/mv-pragma.C: Add CLI flag.
	* g++.target/aarch64/mvc-warning1.C: New test.

0 files changed, 0 insertions, 0 deletions