This also makes the GPU and Skottie portions optional
at build time.
Bug: skia:
Change-Id: I34f494caf0e2ca35dc4767d57f79ba92b24e818f
Reviewed-on: https://skia-review.googlesource.com/c/159146
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
