Some users have a need for old-fashioned setups with multiple X11 Screens
rather then one large virtual Screen as modern X usually has. This can be
accomplished by using multiple qxl devices + a xorg.conf file assigning
one Screen per qxl device.

Limitations:
-Max one monitor per Screen / qxl device
-All monitors / Screens must have the same resolution
-No client -> guest resolution syncing

Signed-off-by: Hans de Goede <hdegoede@redhat.com>