python3-pygobject: enable cairo only when a display is available
It doesn't seem to make sense to unconditionally enable cairo
support, as this pulls in lots of other dependencies, where
none of these can actually be used without some sort of
graphical interface.
Not having a generic distro feature to detect this, we just
use any of DirectFB / Wayland / X11
Signed-off-by: André Draszik <adraszik@tycoint.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
