Signal and release the idle event when the process main thread exits.

diff --git a/server/user.h b/server/user.h
index f3e1060..6d5766e 100644
--- a/server/user.h
+++ b/server/user.h
@@ -43,6 +43,7 @@
 
 /* queue functions */
 
+extern void free_msg_queue( struct thread *thread );
 extern void inc_queue_paint_count( struct thread *thread, int incr );
 extern void queue_cleanup_window( struct thread *thread, user_handle_t win );
 extern void post_message( user_handle_t win, unsigned int message,