rr: no need to search the outbound interface

for single route messages, the outbound interfaces is the same with the
inbound one, so there is no need to search for an outbound socket

(cherry picked from commit b6d4230)

modules/rr/loose.c

@@ -865,16 +865,8 @@ static inline int after_loose(struct sip_msg* _m, int preloaded)
 	status = RR_DRIVEN;
 
 done:
-	if (force_ss) {
-		set_sip_defaults( puri.port_no, puri.proto);
-		si = grep_sock_info( &puri.host, puri.port_no, puri.proto);
-		if (si) {
-			_m->force_send_socket = si;
-		} else {
-			if (enable_socket_mismatch_warning)
-				LM_WARN("no socket found for match second RR\n");
-		}
-	}
+	if (force_ss)
+		_m->force_send_socket = _m->rcv.bind_address;
 	/* run RR callbacks -bogdan */
 	run_rr_callbacks( _m, &routed_params );
 	return status;