avformat/hlsenc: Signal http end of chunk(http_shutdown) during hlsenc_io_close()

Currently http end of chunk is signalled implicitly in hlsenc_io_open().
This mean playlists http writes would have to wait upto a segment duration to signal end of chunk causing delays.
This patch will fix that problem and improve performance.

libavformat/hlsenc.c

@@ -269,8 +269,13 @@ static void hlsenc_io_close(AVFormatContext *s, AVIOContext **pb, char *filename
 
     if (!http_base_proto || !hls->http_persistent || hls->key_info_file || hls->encrypt) {
         ff_format_io_close(s, pb);
+#if CONFIG_HTTP_PROTOCOL
     } else {
+        URLContext *http_url_context = ffio_geturlcontext(*pb);
+        av_assert0(http_url_context);
         avio_flush(*pb);
+        ffurl_shutdown(http_url_context, AVIO_FLAG_WRITE);
+#endif
     }
 }