vp9: Overshoot detection for skipped base layer.

If scene/slide change is detected on current
superframe and max-q set because of high overshoot:
then if the lower/base spatial layer are skipped on
the current superframe, max-q is forced on the
next encoded base/lower spatial layers.

Change-Id: Id61efda86ee545395012e19476d19845e3932678
2 files changed