The commit change to use partitions sizes directly from last frame
for frames directly where last frame selects partitions sizes based
on coding efficiency.
On --rt --cpu-used=-5, the change hurts compression by 4% but reduces
encoding time by ~20%
Change-Id: Ia68665e5c8489b7bfcf5fac7768332fba88928e6
fe0c09c2aa