Added row based loopfilter

Interleaved loopfiltering with decode.  For 1080p clips, up to 1%
performance gain.  For 4k clips, up to 10% seen.  This patch is required
for better "frame-based" multithreading.

Change-Id: Ic834cf32297cc04f27e8205652fb9f70cbe290db
5 files changed