Move Flags from GrRenderTarget to GrTypesPriv.h & rename

The motivation for this is to prevent GrRenderTarget.h appearing in GrRenderTargetProxy.h

Change-Id: I4ef126972c0780cbacb35fa2aa6290777c66eddf
Reviewed-on: https://skia-review.googlesource.com/19521
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
11 files changed