The current way of switching between Xinerama and single-screen handlers
is quite complicated and needs call vector tables that are changed on
the fly, which in turn makes dispatching more complicated.
Reworking this into a simple and straight code flow, where individual request
procs just look at a flag to decide whether to call the Xinerama or single
screen version.
This isn't just much easier to understand (and debug), but also removes the need
or the call vectors, thus allowing further simplification of the dispatcher.
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>