AVX-512. 64/n. Add rest of VI1-AVX2: vpack[us]wb.

AVX-512. 64/n. Add rest of VI1-AVX2: vpack[us]wb.

gcc/
	* config/i386/sse.md
	(define_insn "<sse2_avx2>_packsswb<mask_name>"): Add masking.
	(define_insn "<sse2_avx2>_packuswb<mask_name>"): Ditto.

Co-Authored-By: Andrey Turetskiy <andrey.turetskiy@intel.com>
Co-Authored-By: Anna Tikhonova <anna.tikhonova@intel.com>
Co-Authored-By: Ilya Tocar <ilya.tocar@intel.com>
Co-Authored-By: Ilya Verbin <ilya.verbin@intel.com>
Co-Authored-By: Kirill Yukhin <kirill.yukhin@intel.com>
Co-Authored-By: Maxim Kuznetsov <maxim.kuznetsov@intel.com>
Co-Authored-By: Michael Zolotukhin <michael.v.zolotukhin@intel.com>
From-SVN: r216181