rtp sout: fix race condition in RTSP

When an ES is removed, it is possible to set up a track that won't be
cleaned up and will remain dangling, causing a crash later. Make sure
we unregister the RTSP URL before cleaning up.

modules/stream_out/rtsp.c

@@ -244,6 +244,8 @@ rtsp_stream_id_t *RtspAddId( rtsp_stream_t *rtsp, sout_stream_id_t *sid,
 
 void RtspDelId( rtsp_stream_t *rtsp, rtsp_stream_id_t *id )
 {
+    httpd_UrlDelete( id->url );
+
     vlc_mutex_lock( &rtsp->lock );
     for( int i = 0; i < rtsp->sessionc; i++ )
     {
@@ -261,7 +263,6 @@ void RtspDelId( rtsp_stream_t *rtsp, rtsp_stream_id_t *id )
     }
 
     vlc_mutex_unlock( &rtsp->lock );
-    httpd_UrlDelete( id->url );
     free( id );
 }