Add SkSurface_Graphite stub

and fix up the #include guards

Bug: skia:12466
Change-Id: I865ebb00827001b2cf0f7d871e872a7be0f36c22
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/451156
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
6 files changed