Add a way to force raster pipeline blitter.

    And add some Test/Perf bots to try it out!

CQ_INCLUDE_TRYBOTS=skia.primary:Perf-Ubuntu-Clang-GCE-CPU-AVX2-x86_64-Release-SK_FORCE_RASTER_PIPELINE_BLITTER

Change-Id: I56ea2285f9fec2e468fae89673a545a717ab0f49
Reviewed-on: https://skia-review.googlesource.com/16423
Reviewed-by: Eric Boren <borenet@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
3 files changed