Test suite start to prove its usefulness. (oops).

It should be improved.

src/control/event_async.c

@@ -157,6 +157,12 @@ void
 libvlc_event_async_fini(libvlc_event_manager_t * p_em)
 {    
     if(!is_queue_initialized(p_em)) return;
+
+    if(current_thread_is_asynch_thread(p_em))
+    {
+        fprintf(stderr, "*** Error: releasing the last reference of the observed object from its callback thread is not (yet!) supported\n");
+        abort();
+    }
     
     vlc_thread_t thread = queue(p_em)->thread;
     if(thread)