Make sure spawned thread is joined again

...otherwise, it might still run during exit(3) and cause problems.

dbaccess/source/core/dataaccess/documenteventnotifier.cxx

@@ -165,6 +165,7 @@ namespace dbaccess
         {
             m_pEventBroadcaster->removeEventsForProcessor( this );
             m_pEventBroadcaster->terminate();
+            m_pEventBroadcaster->join();
             m_pEventBroadcaster = NULL;
         }