This adds support for xdg-output-unstable-v1 version 3, added in [1].
This new version deprecates zxdg_output_v1.done and replaces it with
wl_output.done. If the version is high enough, there's no need to wait for both
an xdg_output.done event and a wl_output.done event -- we only care about
wl_output.done.
[1]: 962dd53537
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Olivier Fourdan <ofourdan@redhat.com>