Fix bitmap copy gms

Mark pixels as opaque so copying to 565 continues to work.

Bug: skia:
Change-Id: Id2b0a8c462fe35f7d1cc2ccc32ca10eda18981c8
Reviewed-on: https://skia-review.googlesource.com/14653
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>
2 files changed