Revert rev 1137490: it caused compositing not working with legacy NVIDIA drivers and might be responsible for freezes when changing config.
It can be reverted as there is already a better fix for buggy drivers present in 4.5.1.
Did I mention that I love drivers?
CCBUG: 243991
CCBUG: 241402

svn path=/trunk/KDE/kdebase/workspace/; revision=1167909