Remove kZeroCopy_GrSurfaceFlag

Change-Id: I2869f97a14f3a1363ebfef5d657bd6468fc991f7
Reviewed-on: https://skia-review.googlesource.com/17491
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
3 files changed