simplify and centralize SK_API

Bug: skia:8975
Change-Id: Id45738b178b108593cf931ac236505901e97330a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/207680
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
3 files changed