add compile, use it in blitter

add compile, use it in blitter

I expanded an existing bench to show off the difference:

    SkRasterPipeline_…
    300  …compile 1x  …run 1.14x

Change-Id: I5d63d602cda3f78d2d0891fcc85baf5514632900
Reviewed-on: https://skia-review.googlesource.com/17458
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Herb Derby <herb@google.com>