On Wayland envitonments with Xwayland available but without
ext-data-control-v1, mpv will fall back to the X11 backend instead of
VO backend. This may result in clipboard not working properly between
mpv and native Wayland clients.
Fix this by disabling X11 backend on Wayland envitonments by default
and adding the --clipboard-xwayland option for manual override.
nanahi
1fec44cc6c