i386: Allow 64bit vector modes in general registers

i386: Allow 64bit vector modes in general registers

Allow V8QI, V4HI and V2SI modes in 64bit general registers for
TARGET_64BIT and add alternatives using general registers
to 64bit vector logic instructions.

2021-05-19  Uroš Bizjak  <ubizjak@gmail.com>

gcc/
	* config/i386/i386.h (VALID_INT_MODE_P):
	Add V8QI, V4HI and V2SI modes for TARGET_64BIT.
	* config/i386/i386.md (isa): Add x64_bmi.
	(enabled): Handle x64_bmi.
	* config/i386/mmx.md (mmx_andnot<MMXMODEI:mode>3):
	Add alternative using 64bit general registers.
	(*mmx_<any_logic:code><MMXMODEI:mode>3): Ditto.