Revert "Revert "Return POD from generateMetrics() rather than mutate SkGlyph""

This reverts commit 3b83ce679ed656c3a347aec594f111170e0077de.

Fix was to copy over extraBits from glyph to glyphmetrics

Change-Id: Iaf771d2461544936b380911f7dca65cbbbb444bb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/729800
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
17 files changed