vp9-svc: Fix to postencode drop for layers.

Postencode drop is only checked on base spatial
layers, and if set, whole superframe is dropped and
and next superframe is encoded at max-q.

Fix here is to make sure all layers are encoded at
max-q on a postencode dropped frame.

Change-Id: I2313d83ee29a382465bcec1085d8c73c37ce26d6
1 file changed