ffserver: fixed deallocation bug in build_feed_streams

Signed-off-by: Gregor Riepl <onitake@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

ffserver.c

@@ -3863,6 +3863,8 @@ drop:
             if (avformat_write_header(s, NULL) < 0) {
                 http_log("Container doesn't support the required parameters\n");
                 avio_closep(&s->pb);
+                s->streams = NULL;
+                s->nb_streams = 0;
                 avformat_free_context(s);
                 goto bail;
             }