AVX-512. Add byte/word plus/minus/avg.

AVX-512. Add byte/word plus/minus/avg.

gcc/
	(define_mode_iterator VI12_AVX2): Add V64QI and V32HI modes.
	(define_expand "<sse2_avx2>_<plusminus_insn><mode>3<mask_name>"): Add
	masking.
	(define_insn "*<sse2_avx2>_<plusminus_insn><mode>3<mask_name>"): Ditto.
	(define_expand "<sse2_avx2>_uavg<mode>3<mask_name>"): Ditto.
	(define_insn "*<sse2_avx2>_uavg<mode>3<mask_name>"): Ditto.
	(define_insn "*mul<mode>3"): Add EVEX version.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@214672 138bc75d-0d04-0410-961f-82ee72b054a4