Add GFNI command line options and macros

Add GFNI command line options and macros

gcc/
	* common/config/i386/i386-common.c (OPTION_MASK_ISA_GFNI_SET,
	(OPTION_MASK_ISA_GFNI_UNSET): New.
	(ix86_handle_option): Handle OPT_mgfni.
	* config/i386/cpuid.h (bit_GFNI): New.
	* config/i386/driver-i386.c (host_detect_local_cpu): Detect gfni.
	* config/i386/i386-c.c (ix86_target_macros_internal): Define __GFNI__.
	* config/i386/i386.c (ix86_target_string): Add -mgfni.
	(ix86_valid_target_attribute_inner_p): Add OPT_mgfni.
	* config/i386/i386.h (TARGET_GFNI, TARGET_GFNI_P): New.
	* config/i386/i386.opt: Add mgfni.

From-SVN: r253922