avformat/hlsenc: make the EXT-X-MEDIA NAME field by stream id.

Signed-off-by: Steven Liu <lq@chinaffmpeg.org>

libavformat/hlsenc.c

@@ -1258,7 +1258,7 @@ static int create_master_playlist(AVFormatContext *s,
             goto fail;
         }
 
-        ff_hls_write_audio_rendition(hls->m3u8_out, vs->agroup, m3u8_rel_name, 0, 1);
+        ff_hls_write_audio_rendition(hls->m3u8_out, vs->agroup, m3u8_rel_name, i, 1);
 
         av_freep(&m3u8_rel_name);
     }