Make tests compile without gui-private

Make tests compile without gui-private

Add new qt_handleXXX functions that forward to the QWindowSystemInterface
functions, and use those in the testlib inline functions. Remove use of
struct QWindowSystemInterface::TouchPoint from the testlib header files
(requiring some slight increase in ugliness in the two tests that use
that struct).

Also remove the qmake hack that adds private headers to all tests

Change-Id: Iec23537e55a44802f6e9cd463f7a0f82007c5250
Reviewed-by: Paul Olav Tvete <paul.tvete@nokia.com>