VAAPI: separate module from avcodec
The VLC avcodec plugin links with vaapi-x11. This makes the entire avcodec plugin dependent on X11. There has been a lot of confusion on Debian/Ubuntu with the move of avcodec from vlc-nox to vlc in headless VLC use cases.
libavcodec proper only needs libva, not libva-x11. The VLC plugin should exhibit the same dependency. There are two ways to achieve this:
- a plugin capability for lavc/vlc HW back-end (VAAPI, DxVA2, ...),
- a plugin capability for VAAPI windowing system (X11, EGL...)