Add SK_API to APIs used by the android framework.

This CL enables us to set the default visibility of the symbols
on Android to hidden.  It is the intent that all of he SK_APIs
that have been added to /src directies should be removed as soon
as we can remove their callers within Android.

Bug: b/31971097
Change-Id: Ic787f94df0fb0c2b8d941aa7095a12b317c4b5de
Reviewed-on: https://skia-review.googlesource.com/49501
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Derek Sollenberger <djsollen@google.com>
19 files changed