Fix crash on RTSP error with TS muxing (CID#179)

(cherry picked from commit 9087d31f)

modules/stream_out/rtp.c

@@ -637,10 +637,8 @@ static void SDPHandleUrl( sout_stream_t *p_stream, const char *psz_url )
         /* FIXME test if destination is multicast or no destination at all */
         p_sys->rtsp = RtspSetup( p_stream, &url );
         if( p_sys->rtsp == NULL )
-        {
             msg_Err( p_stream, "cannot export SDP as RTSP" );
-        }
-
+        else
         if( p_sys->p_mux != NULL )
         {
             sout_stream_id_t *id = p_sys->es[0];