AArch64: fix ls64 intrinsics expansion [PR104409]

AArch64: fix ls64 intrinsics expansion [PR104409]

The LS64 intrinsics used a machinery that's not safe to use unless being
called from a pragma instantiation.

This moves the initialization code to a new pragma for arm_acle.h.

gcc/ChangeLog:

	PR target/104409
	* config/aarch64/aarch64-builtins.cc (handle_arm_acle_h): New.
	(aarch64_general_init_builtins): Move LS64 code.
	* config/aarch64/aarch64-c.cc (aarch64_pragma_aarch64): Support
	arm_acle.h
	* config/aarch64/aarch64-protos.h (handle_arm_acle_h): New.
	* config/aarch64/arm_acle.h: Add pragma GCC aarch64 "arm_acle.h".