ii386: Add missing two element 64bit vector permutations [PR89021]

ii386: Add missing two element 64bit vector permutations [PR89021]

In addition to V8QI permutations, several other missing permutations are
added for 64bit vector modes for TARGET_SSSE3 and TARGET_SSE4_1 targets.

2021-06-16  Uroš Bizjak  <ubizjak@gmail.com>

gcc/
	PR target/89021
	* config/i386/i386-expand.c (expand_vec_perm_2perm_pblendv):
	Handle 64bit modes for TARGET_SSE4_1.
	(expand_vec_perm_pshufb2): Handle 64bit modes for TARGET_SSSE3.
	(expand_vec_perm_even_odd_pack): Handle V4HI mode.
	(expand_vec_perm_even_odd_1) <case E_V4HImode>: Expand via
	expand_vec_perm_pshufb2 for TARGET_SSSE3 and via
	expand_vec_perm_even_odd_pack for TARGET_SSE4_1.
	* config/i386/mmx.md (mmx_packusdw): New insn pattern.