Change only affects 1 pass, vbr, speed = 5 (real-time mode).

Some improvement for high motion content.
AvgPSNR/SSIM metrics for ytlive set all up, on average ~2%,
some clips (high motion ones) up 4/5%.

Encoder speed down: on mynintendo_x1.1280_720.y4m: 47fps -> 44fps.

Change-Id: I9e3eaa6392dcb6b5b44ee6f43004f97ba859bc11