Handle absolute ConfigureNotify events for parent window

For VST2 in Ardour, it seems Ardour is doing its own WM/wrapper window
thing too. In this case, the plugin gets absolute ConfigureNotify events
that are already in the root coordinate space, so just use those
coordinates and ignore the host window.

Also fix the dimensions, which should always be those of the parent
window, not the host window. If the parent is the host window, still
track its geometry separately, and just don't add in the host window
dimensions in this case either.

src/wine-host/editor.h

@@ -343,6 +343,7 @@ class Editor {
      */
     xcb_configure_notify_event_t host_window_config_;
     xcb_configure_notify_event_t parent_window_config_;
+    bool parent_window_config_abs_;
 
     /**
      * The handle for the window created through Wine that the plugin uses to