[dev.simd] simd: fix signatures for PermuteConstant* methods
This moves the packed-immediate methods to package-private,
and adds exported versions with four parameters.
Rename PermuteConstant to PermuteScalars
Rename VPSHUFB Permute to PermuteOrZero
Rename Permute2 to ConcatPermute
Comments were repaired/enhanced.
Modified the generator to support an additional tag
"hideMaskMethods : true" to suppress method, intrinsic,
generic, and generic translation generation for said
mask-modified versions of such methods (this is already
true for exported methods).
Change-Id: I91e208c1fff1f28ebce4edb4e73d26003715018c
Reviewed-on: https://go-review.googlesource.com/c/go/+/721342
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Junyang Shao <shaojunyang@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>