arm: add armv9-a architecture to -march

arm: add armv9-a architecture to -march

In this patch:
	+ Add `armv9-a` to -march.
	+ Update multilib with armv9-a and armv9-a+simd.

gcc/ChangeLog:

	* config/arm/arm-cpus.in (armv9): New define.
	(ARMv9a): New group.
	(armv9-a): New arch definition.
	* config/arm/arm-tables.opt: Regenerate.
	* config/arm/arm.h (BASE_ARCH_9A): New arch enum value.
	* config/arm/t-aprofile: Added armv9-a and armv9+simd.
	* config/arm/t-arm-elf: Added arm9-a, v9_fps and all_v9_archs
	to MULTILIB_MATCHES.
	* config/arm/t-multilib: Added v9_a_nosimd_variants and
	v9_a_simd_variants to MULTILIB_MATCHES.
	* doc/invoke.texi: Update docs.

gcc/testsuite/ChangeLog:

	* gcc.target/arm/multilib.exp: Update test with armv9-a entries.
	* lib/target-supports.exp (v9a): Add new armflag.
	(__ARM_ARCH_9A__): Add new armdef.