avformat/http : Added check for valid URL context before calling shutdown

libavformat/http.c

@@ -1650,7 +1650,7 @@ static int http_close(URLContext *h)
     av_freep(&s->inflate_buffer);
 #endif /* CONFIG_ZLIB */
 
-    if (!s->end_chunked_post)
+    if (s->hd && !s->end_chunked_post)
         /* Close the write direction by sending the end of chunked encoding. */
         ret = http_shutdown(h, h->flags);