start excising xbyak

I'm hoping to remove xbyak bit by bit, like the ship of Theseus
or some petrified wood, leaving a functioning homegrown JIT.

This starts with some of the easier instructions, still using
xbyak to accumulate the code buffer, just with db() directly.

  - ret
  - vzeroupper
  - align with noops

Change-Id: I9443bc5191cb1d75b8871d174ccf15ac7e96e9a5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/221613
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed