m_windowManagerListener is unused variable

There is already a variable named "windowmanager_listener"

Change-Id: I40bfb42a5b0b35d0d8851f0baa6f3741b47ae57e
Reviewed-by: Jørgen Lind <jorgen.lind@nokia.com>

src/plugins/platforms/wayland/windowmanager_integration/qwaylandwindowmanagerintegration.h

@@ -88,8 +88,6 @@ class QWaylandWindowManagerIntegration : public QObject, public QPlatformService
                              int32_t showIsFullScreen);
     static void handle_quit(void *data, struct wl_windowmanager *ext);
 
-    static const struct wl_windowmanager_listener m_windowManagerListener;
-
     void openUrl_helper(const QUrl &url);
 };