Currently, the trend is to get the coordinates of the hotspot and map it
to the device independent pixels at the call site.
This change makes the KXcursorSprite return the coordinates of the hotspot
in the device independent pixels to reduce the amount of duplicated code.
Currently in order to load an Xcursor theme, kwin uses libwayland api,
which looks really awkward because of the way how the compositor talks
to itself via the internal connection.
The main motivation behind this change is to limit the usage of kwayland
client api in kwin.