i386.md (isa): Add x64_avx512dq, enable if TARGET_64BIT && TARGET_AVX512DQ.

i386.md (isa): Add x64_avx512dq, enable if TARGET_64BIT && TARGET_AVX512DQ.

	* config/i386/i386.md (isa): Add x64_avx512dq, enable if
	TARGET_64BIT && TARGET_AVX512DQ.
	* config/i386/sse.md (*vec_extract<mode>): Add avx512bw alternatives.
	(*vec_extract<PEXTR_MODE12:mode>_zext): Add avx512bw alternative.
	(*vec_extract<ssevecmodelower>_0, *vec_extractv4si_0_zext,
	*vec_extractv2di_0_sse): Use v constraint instead of x constraint.
	(*vec_extractv4si): Add avx512dq and avx512bw alternatives.
	(*vec_extractv4si_zext): Add avx512dq alternative.
	(*vec_extractv2di_1): Add x64_avx512dq and avx512bw alternatives,
	use v instead of x constraint in other alternatives where possible.

	* gcc.target/i386/avx512bw-vpextr-1.c: New test.
	* gcc.target/i386/avx512dq-vpextr-1.c: New test.

From-SVN: r236167