[dev.simd] cmd/compile, simd: add definitions for VPTERNLOG[DQ]

[dev.simd] cmd/compile, simd: add definitions for VPTERNLOG[DQ]

This includes an non-public intrinsic for testing,
and a test.  Optimizations using this instruction
will follow in another CL.

Change-Id: I7f7a93212249a16a30bd1379c717f8a7f9915daf
Reviewed-on: https://go-review.googlesource.com/c/go/+/708995
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Junyang Shao <shaojunyang@google.com>