Merge commit '851960f6'

* commit '851960f6':
  lavc: Remove old vaapi decode infrastructure
  avconv_vaapi: Convert to use hw_frames_ctx only
  vaapi_mpeg4: Convert to use the new VAAPI hwaccel code
  vaapi_vc1: Convert to use the new VAAPI hwaccel code
  vaapi_mpeg2: Convert to use the new VAAPI hwaccel code
  vaapi_h264: Convert to use the new VAAPI hwaccel code
  lavc: Rewrite VAAPI decode infrastructure

This merge is a noop, these commits have already been cherry-picked.
Merged-by: Clément Bœsch <u@pkh.me>