xfce4-settings: Update to latest stable version 4.8.3.

http://git.xfce.org/xfce/xfce4-settings/tag/?id=xfce4-settings-4.8.3



Run tested on netbook pro.

Signed-off-by: Peter Tworek <tworaz666@gmail.com>
Acked-by: Andreas Müller <schnitzeltony@googlemail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>