[3.20] community/ffmpeg: add fixes for VA-API

Mesa 24.0.6+ is triggering this bug.

Patchset-url: https://patchwork.ffmpeg.org/project/ffmpeg/list/?series=11693 Ref: https://gitlab.freedesktop.org/mesa/mesa/-/issues/11197

Signed-off-by: David Heidelberg david@ixit.cz