Make the QtTest GUI headers compile on their own

Though no one is supposed to include them directly, it's a good idea
to ensure that they are tested too. They're only included from the
master header when QT_GUI_LIB and QT_WIDGETS_LIB are #defined.

Change-Id: Ie84bb6fd4c18b5b51ab35463f9082feaa0693c97
Reviewed-by: Harald Fernengel <harald.fernengel@nokia.com>

src/testlib/qtestmouse.h

@@ -54,6 +54,7 @@
 #include <QtCore/qpoint.h>
 #include <QtCore/qstring.h>
 #include <QtGui/qevent.h>
+#include <QtGui/qwindow.h>
 
 #ifdef QT_WIDGETS_LIB
 #include <QtWidgets/qapplication.h>

src/testlib/qtesttouch.h

@@ -53,6 +53,7 @@
 #include <QtTest/qtestspontaneevent.h>
 #include <QtCore/qmap.h>
 #include <QtGui/qevent.h>
+#include <QtGui/qwindow.h>
 #ifdef QT_WIDGETS_LIB
 #include <QtWidgets/qwidget.h>
 #endif