aarch64: Add support for Armv8-R

aarch64: Add support for Armv8-R

This adds support for Armv8-R AArch64 to GCC. It adds the -march value
armv8-r and sets the ACLE feature macro __ARM_ARCH_PROFILE correctly
when -march is set to armv8-r.

gcc/ChangeLog:

	* common/config/aarch64/aarch64-common.c
	(aarch64_get_extension_string_for_isa_flags): Don't force +crc for
	Armv8-R.
	* config/aarch64/aarch64-arches.def: Add entry for Armv8-R.
	* config/aarch64/aarch64-c.c (aarch64_define_unconditional_macros): Set
	__ARM_ARCH_PROFILE correctly for Armv8-R.
	* config/aarch64/aarch64.h (AARCH64_FL_V8_R): New.
	(AARCH64_FL_FOR_ARCH8_R): New.
	(AARCH64_ISA_V8_R): New.
	* doc/invoke.texi: Add Armv8-R to architecture table.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/acle/armv8-r.c: New test.