all: VPCLMULQDQ instruction (#360)

Adds VEX and EVEX encoded versions of the `PCLMULQDQ` carry-less quadword
multiplication instruction.

These are added via the `opcodesextra` mechanism #345, since they're missing
from the opcodes database.

Contributed by @vsivsi. Extracted from #349 with minor tweaks.

Co-authored-by: Vaughn Iverson <vsivsi@yahoo.com>

internal/opcodesextra/instructions.go

@@ -9,6 +9,7 @@ var sets = [][]*inst.Instruction{
 	gfni,
 	vaes,
 	vnni,
+	vpclmulqdq,
 }
 
 // Instructions returns a list of extras to add to the instructions database.