Simplify more: remove SkRasterPipeline::compile().

Simplify more: remove SkRasterPipeline::compile().

It's easier to work on SkJumper if everything funnels through run().

I don't anticipate huge benefit from compile() without JITing,
but it's something we can always put back if we find a need.

Change-Id: Id5256fd21495e8195cad1924dbad81856416d913
Reviewed-on: https://skia-review.googlesource.com/8468
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>