FEI encoders are not actively mantained neither tested, and it is
using infrastructure that is changing and FEI is stopping this
effort.
Also it is required to rethink how FEI can be used in GStreamer.
The context overlay was an optimization to apply a video composition
to all the surfaces bound to a context.
But since commit 18031dc6 this optimization was disabled, so it is
better just get rid of it.
[wl_shell] is officially [deprecated], so provide support for the
XDG-shell protocol should be provided by all desktop-like compositors.
(In case they don't, we can of course fall back to wl_shell).
Note that the XML file is directly provided by the `wayland-protocols`
dependency and generates the protocol marshalling code.
[wl_shell]: https://people.freedesktop.org/~whot/wayland-doxygen/wayland/Client/group__iface__wl__shell.html
[deprecated]: 698dde1958
Since there is duplicated code in h264/265 encoder, we could
refactor it to avoid duplicated code.
https://bugzilla.gnome.org/show_bug.cgi?id=778750
Signed-off-by: Víctor Manuel Jáquez Leal <victorx.jaquez@intel.com>