Port optimize_b cache optimizations to AV1.

Bring the following libvpx commits to aom:
e446ffd Cache optimizations in optimize_b()
50d3629 Repack vp9_token_state

Saves 24600 bytes of stack in the default configuration.

Change-Id: If9d6506cf3fe1c34ab639dedb3ef62a996293781
1 file changed