transition to enum class for SkFontHinting

Bug: skia:8527
Change-Id: I8c1f2b9d97b51ca577c2e912c6cb048f5b6e2dc4
Reviewed-on: https://skia-review.googlesource.com/c/168760
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
3 files changed