AVX-512. 74/n. Add byte/word max/mix reduction.

AVX-512. 74/n. Add byte/word max/mix reduction.

gcc/
	* config/i386/i386.c
	(emit_reduc_half): Handle V64QI and V32HI mode.
	* config/i386/sse.md
	(define_mode_iterator VI_AVX512BW): New.
	(define_expand "reduc_<code>_<mode>"): Use VI512_48F_12BW.

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: r216192