winex11: Set size hints to 1x1 for zero-sized windows.

dlls/winex11.drv/window.c

@@ -1018,6 +1018,8 @@ static void set_size_hints( Display *display, struct x11drv_win_data *data, DWOR
         {
             size_hints->max_width = data->whole_rect.right - data->whole_rect.left;
             size_hints->max_height = data->whole_rect.bottom - data->whole_rect.top;
+            if (size_hints->max_width <= 0 ||size_hints->max_height <= 0)
+                size_hints->max_width = size_hints->max_height = 1;
             size_hints->min_width = size_hints->max_width;
             size_hints->min_height = size_hints->max_height;
             size_hints->flags |= PMinSize | PMaxSize;