[AArch64] Break -mcpu tie between the compiler and assembler

[AArch64] Break -mcpu tie between the compiler and assembler

gcc/

	* common/config/aarch64/aarch64-common.c
	(AARCH64_CPU_NAME_LENGTH): Delete.
	(aarch64_option_extension): New.
	(all_extensions): Likewise.
	(processor_name_to_arch): Likewise.
	(arch_to_arch_name): Likewise.
	(all_cores): New.
	(all_architectures): Likewise.
	(aarch64_get_extension_string_for_isa_flags): Likewise.
	(aarch64_rewrite_selected_cpu): Change to rewrite CPU names to
	architecture names.
	* config/aarch64/aarch64-protos.h
	(aarch64_get_extension_string_for_isa_flags): New.
	* config/aarch64/aarch64.c (aarch64_print_extension): Delete.
	(aarch64_option_print): Get the string to print from
	aarch64_get_extension_string_for_isa_flags.
	(aarch64_declare_function_name): Likewise.
	* config/aarch64/aarch64.h (BIG_LITTLE_SPEC): Rename to...
	(MCPU_TO_MARCH_SPEC): This.
	(ASM_CPU_SPEC): Use it.
	(BIG_LITTLE_SPEC_FUNCTIONS): Rename to...
	(MCPU_TO_MARCH_SPEC_FUNCTIONS): ...This.
	(EXTRA_SPEC_FUNCTIONS): Use it.

From-SVN: r227028