All changes are for spatial svc only.
1. Enable encoding hidden frames in each layer and use alt reference idex to reference the hidden frame in each layer
2. Use golden reference idx for spatial reference
3. For those layers that don't have hidden frames (caused by lack of frame buffers), reference a hidden frame in lower layers
4. Add "auto-alt-refs" in svc options
Change-Id: Idf27d1fd2fb5f3ffd9e86d2119235e3dad36c178
1. Save stats for each spatial layer
2. Add frame buffer management for svc first pass rc
3. Set default spatial layer to 1
4. Flush encoder at the end of stream in test app
This only supports spatial svc.
Change-Id: Ia89cfa87bb6394e6c0405b921d86c426d0a0c9ae
