[AArch64 1/3 big.LITTLE] Driver rewriting of big.LITTLE names.

[AArch64 1/3 big.LITTLE] Driver rewriting of big.LITTLE names.

gcc/

	* common/config/aarch64/aarch64-common.c
	(aarch64_rewrite_selected_cpu): New.
	(aarch64_rewrite_mcpu): New.
	* config/aarch64/aarch64-protos.h
	(aarch64_rewrite_selected_cpu): New.
	* config/aarch64/aarch64.h (BIG_LITTLE_SPEC): New.
	(BIG_LITTLE_SPEC_FUNCTIONS): Likewise.
	(ASM_CPU_SPEC): Likewise.
	(EXTRA_SPEC_FUNCTIONS): Likewise.
	(EXTRA_SPECS): Likewise.
	(ASM_SPEC): Likewise.
	* config/aarch64/aarch64.c (aarch64_start_file): Rewrite target
	CPU name.

From-SVN: r206098