Qt51fix

This patch is temporary solution for Qt5.1 compatibility issues. It makes SDDM at least usable wit Qt5.1.
- Flickering: for some reason it resolves when screen size isn't equal to window size;
- No pointer/X pointer: seems like Qt5.1 doesn't set root window cursor anymore (not sure if its is bug or not).

So there are 2 ugly workarounds, however one can be improved, if we will properly change root cursor via xcb.