move skvm interpreter to SkOpts again

This is the easiest way to guarantee Op::fma_f32
actually fuses, by using platform intrinsics.

While implementing this we noticed that quad-pumping
was actually slower than double-pumping by about 25%,
and single-pumping was between the two.  Switch from
quad to double pumping.

Change-Id: Ib93fd175fb8f6aaf49f769a95edfa9fd6b2674f6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/275299
Commit-Queue: Mike Klein <mtklein@google.com>
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Herb Derby <herb@google.com>
7 files changed