[dev.simd] simd: add emulations for bitwise ops and for mask/merge methods
This CL adds the emulations under a "wrong name"; subsequent CLs
will move the AVX512 versions of these operations out of the way,
and then will rename these to their better names.
Change-Id: I49e7a73e4fea74fb7bd26cb8062014568d7999ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/692217 Reviewed-by: Junyang Shao <shaojunyang@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>