(iconify_event, deiconify_event): New events.

src/termhooks.h

@@ -248,10 +248,12 @@ enum event_kind
   selection_clear_event,	/* Another X client cleared our selection.  */
   buffer_switch_event,		/* A process filter has switched buffers.  */
   delete_window_event,		/* An X client said "delete this window".  */
-  menu_bar_event		/* An event generated by the menu bar.
+  menu_bar_event,		/* An event generated by the menu bar.
 				   The frame_or_window field holds the
 				   Lisp-level event value.
 				   (Only the toolkit version uses these.)  */
+  iconify_event,		/* An X client iconified this window.  */
+  deiconify_event		/* An X client deiconified this window.  */
 };
 
 /* If a struct input_event has a kind which is selection_request_event