AVX-512. 89/n. Improve mask move insn generation.

gcc/
	* config/i386/i386.md
	(movhi_internal): Always detect maskmov.
	(movqi_internal): Fix target check.
gcc/testsuite/
	* gcc.target/i386/avx512dq-kmovb-1.c: New.

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: r216820