arm: remove unnecessary armv9-a multilib variant [PR104144]

arm: remove unnecessary armv9-a multilib variant [PR104144]

Remove the armv9-a specific multilib variants.  Instead, arrange to
use either the armv8-a multilibs or the armv7-a versions, depeding on
the configuration.  This eliminates the need to have a version of gas
that understands --march=armv9-a when building GCC.  Very little, if
anything in the standard libraries directly uses Armv9-a features
anyway.

Also remove the +crc variant rules for Armv9-a.  CRC is an implicit
part of Armv9-a, so doesn't have a explicit feature to handle it.

gcc/ChangeLog:

	PR target/104144
	* config/arm/t-aprofile (MULTI_ARCH_OPTS_A): Remove Armv9-a options.
	(MULTI_ARCH_DIRS_A): Remove Armv9-a diretories.
	(MULTILIB_REQUIRED): Don't require Armv9-a libraries.
	(MULTILIB_MATCHES): Treat Armv9-a as equivalent to Armv8-a.
	(MULTILIB_REUSE): Remove remap rules for Armv9-a.
	* config/arm/t-multilib (v9_a_nosimd_variants): Delete.
	(MULTILIB_MATCHES): Remove mappings for v9_a_nosimd_variants.

gcc/testsuite/ChangeLog:

	PR target/104144
	* gcc.target/arm/multilib.exp: Updated tests.