glamor: Improve glyphs cache mechanism.
This commit applying the latest uxa's glyphs cache mechanism and give up the old hash based cache algorithm. And the cache picture now is much larger than the previous one also. This new algorithm can avoid the hash insert/remove and also the expensive sha1 checking. It could obtain about 10% performance gain when rendering glyphs. Signed-off-by: Zhigang Gong <email@example.com>