Offscreen: Protect against the QT_NO_CURSOR define for changeCursor

If QT_NO_CURSOR is defined then changeCursor() is not implemented in
QPlatformCursor which means that it isn't really being overridden in the
offscreen plugin. Therefore the same define is checked for to prevent a
compiler from having a problem with it.

Change-Id: Id7c104292354cb7462b3161602fc8d382a6dd390
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

src/plugins/platforms/offscreen/qoffscreencommon.cpp

@@ -75,13 +75,13 @@ public:
 
         QOffscreenScreen::windowContainingCursor = containing ? containing->handle() : 0;
     }
-
+#ifndef QT_NO_CURSOR
     void changeCursor(QCursor *windowCursor, QWindow *window) Q_DECL_OVERRIDE
     {
         Q_UNUSED(windowCursor);
         Q_UNUSED(window);
     }
-
+#endif
 private:
     QPoint m_pos;
 };