handle_ruri_alias for internal in-dialog

* a in-dialog from internal where loose_route() fails can still be routed if we have the alias for the contact

(cherry picked from commit a718d0349e)

kamailio/default.cfg

@@ -466,6 +466,11 @@ route[HANDLE_IN_DIALOG_REQUESTS]
         route(RELAY);
     } else if (isflagset(FLAG_INTERNALLY_SOURCED)) {
         xlog("L_INFO", "$ci|log|relay internally sourced in-dialog message without loose_route\n");
+        #!ifdef NAT_TRAVERSAL_ROLE
+        if(!isdsturiset()) {
+            handle_ruri_alias();
+        }
+        #!endif
         route(RELAY);
     } else if (t_check_trans()) {
         xlog("L_INFO", "$ci|log|allow message for a known transaction\n");