As discussed on mailing list and QtCS 2012.
Any file starting with qwindowsystem is now marked as
QPA API.
This change drops _qpa from the filenames and adds gui-private
where required for the code to compile. This change is backward
compatible otherwise and compat headers are created for
the old inclusion headers.
Change-Id: I72ea0f394dee74f46e614fcf11ab5500ac9fef2a
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>