Win32: return a failure when a CHANGE_DISPLAY_SIZE event is forced

See x11.c for rationale.

Close #9273
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/video_output/msw/common.c

@@ -588,6 +588,7 @@ int CommonControl(vout_display_t *vd, int query, va_list args)
                              rect_window.right - rect_window.left,
                              rect_window.bottom - rect_window.top, SWP_NOMOVE);
             }
+            return VLC_EGENERIC;
         }
         UpdateRects(vd, cfg, source, is_forced);
         return VLC_SUCCESS;