call skcms_OptimizeForSpeed()

I've guarded src and dst separately, so that we can land,
rebaseline just the src change, and then later (when it
does something), rebaseline optimizing dst separately.

Small threshold tweak to keep a unit test passing.

Change-Id: I57cc43c54b6065f58fa8f9448ea1d73fc42505f0
Reviewed-on: https://skia-review.googlesource.com/123181
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>
2 files changed