Add support for Loongson 3A1000 processor.

Add support for Loongson 3A1000 processor.

gcc/
	* config/mips/loongson3a.md: Rename to ...
	* config/mips/gs464.md: ... here.
	* config/mips/mips-cpus.def: Define gs464; Add loongson3a
	as an alias of gs464 processor.
	* config/mips/mips-tables.opt: Regenerate.
	* config/mips/mips.c (mips_issue_rate): Use PROCESSOR_GS464
	instead of PROCESSOR_LOONGSON_3A.
	(mips_multipass_dfa_lookahead): Use TUNE_GS464 instead of
	TUNE_LOONGSON_3A.
	(mips_option_override): Enable MMI and EXT for gs464.
	* config/mips/mips.h: Rename TARGET_LOONGSON_3A to TARGET_GS464;
	Rename TUNE_LOONGSON_3A to TUNE_GS464.
	(MIPS_ISA_LEVEL_SPEC): Infer mips64r2 from gs464.
	(ISA_HAS_ODD_SPREG, ISA_AVOID_DIV_HILO, ISA_HAS_FUSED_MADD4,
	ISA_HAS_UNFUSED_MADD4): Use TARGET_GS464 instead of
	TARGET_LOONGSON_3A.
	* config/mips/mips.md: Include gs464.md instead of loongson3a.md.
	(processor): Add gs464;
	* doc/invoke.texi: Add gs464 to supported architectures.

From-SVN: r265865