Remove some SK_API from src/

There are still some present (being used by Chromium or Android),
but I think all of these are internal-only.

Change-Id: I80177a65e0ea737e88ab7bb1ef36d03edebd4fa4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/255138
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
9 files changed