Speed up filter-intra keyframe encoding with model RD
Speed up filter-intra keyframe encoding with model RD

On keyframe, 22% speedup, 0.04% compression loss.

Change-Id: I70d387cc9de86c0c0c8b0037d35cff141409d59b

smarter/aom,GrokImageCompression/aom,luctrudeau/aom,luctrudeau/aom,GrokImageCompression/aom,luctrudeau/aom,GrokImageCompression/aom,smarter/aom,smarter/aom,luctrudeau/aom,luctrudeau/aom,GrokImageCompression/aom,GrokImageCompression/aom,luctrudeau/aom,smarter/aom,smarter/aom,GrokImageCompression/aom,smarter/aom