VP9 SVC: Add control to disable inter layer prediction.

VP9 SVC: Add control to disable inter layer prediction.

Add VP9E_SET_SVC_INTER_LAYER_PRED to disable inter layer (spatial)
prediction.
0: prediction on
1: prediction off for all frames
2: prediction off for non key frames

Bump up ABI version.

Change-Id: I5ab2a96b47e6bef202290fe726bed5f99bd4951f