Merge commit '956a5412'

* commit '956a5412':
  vaapi_h264: Set max_num_ref_frames to 1 when not using B frames
  vaapi_encode: Sync to input surface rather than output
  vaapi_encode: Check packed header capabilities
  vaapi_encode: Refactor initialisation

This merge is a noop, see:

ee1d04f9 vaapi_h264: Set max_num_ref_frames to 1 when not using B frames
94f446c6 vaapi_encode: Sync to input surface rather than output
478a4b7e vaapi_encode: Check packed header capabilities
c8241e73 vaapi_encode: Refactor initialisation
Merged-by: Clément Bœsch <u@pkh.me>