expore flags for text decoration into android-specific reserved bits

BUG=skia:6250

precursor to https://skia-review.googlesource.com/c/8815/

Change-Id: I0ff13ff99299edcb7809a2088e0ace61bc8cc60d
Reviewed-on: https://skia-review.googlesource.com/8816
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed