lavf/hls: add AC-3/EAC-3 to allowed extensions file list

Add AC-3/EAC-3 to allowed extensions file list.

From HTTP Live Streaming 2nd Edition draft-pantos-hls-rfc8216bis-07
section 3.1.3.Packed Audio, HLS demuxer need to support MP3/AC-3/EAC-3.

Reviewd-by: Steven Liu <liuqi05@kuaishou.com>
Signed-off-by: Jun Zhao <barryjzhao@tencent.com>

libavformat/hls.c

@@ -2371,7 +2371,7 @@ static const AVOption hls_options[] = {
         OFFSET(live_start_index), AV_OPT_TYPE_INT, {.i64 = -3}, INT_MIN, INT_MAX, FLAGS},
     {"allowed_extensions", "List of file extensions that hls is allowed to access",
         OFFSET(allowed_extensions), AV_OPT_TYPE_STRING,
-        {.str = "3gp,aac,avi,flac,mkv,m3u8,m4a,m4s,m4v,mpg,mov,mp2,mp3,mp4,mpeg,mpegts,ogg,ogv,oga,ts,vob,wav"},
+        {.str = "3gp,aac,avi,ac3,eac3,flac,mkv,m3u8,m4a,m4s,m4v,mpg,mov,mp2,mp3,mp4,mpeg,mpegts,ogg,ogv,oga,ts,vob,wav"},
         INT_MIN, INT_MAX, FLAGS},
     {"max_reload", "Maximum number of times a insufficient list is attempted to be reloaded",
         OFFSET(max_reload), AV_OPT_TYPE_INT, {.i64 = 1000}, 0, INT_MAX, FLAGS},