If the XVideo driver does not provide any RGB image format, then we
are definitely better off with GLX than XVideo. Consider:
 - GLX supports proper subpicture blending - not XVideo,
 - GLX does not need chroma conversion - XVideo does in this case.

This change makes no difference if the XVideo driver supports RGB.

The core cannot blend subpictures to hardware surfaces. In principles,
blending could be performed post chroma conversion, but this is not
supported by the video output wrapper so far.

This is required for wl_surface.set_buffer_transform.

Note: The wl_scaler object is retained after Open() even though it is
not currently used afterwards. It will probably be needed for scaling
subpictures going forward.

Signed-off-by: David Fuhrmann <dfuhrmann@videolan.org>

if Realloc fails, we are anyway screwed and most of the code doesn't
chec check for Realloc failures even in this module.

That should help failing safe to software decoding if the graphic card
has too little free memory. Old cards with only 256 MiB are commonly
affected by that problem.

This seems necessary to maintain the mapping of libav's packet stream
index to the VLC plugin's tracks table offset.

strncpy triggers warning because the
struct is nonzero terminated.

There's no reason to wait 6 sec for a reply
to a spontaneous ping. The reply has no
relation with the 5 sec keepalive ping sent from
the receiver.

The function remain fundamentally ToCToU-prone, but at least they now
follow the memory model.

Loading the open nib can take some significant time, due to audio/
video devices enumeration.

refs #12123

Stop sending and disconnect when app has changed.