avformat/movenc: write stss boxes for xHE-AAC

This is in preparation for a following change.

Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/movenc.c

@@ -3204,6 +3204,7 @@ static int mov_write_stbl_tag(AVFormatContext *s, AVIOContext *pb, MOVMuxContext
     if ((track->par->codec_type == AVMEDIA_TYPE_VIDEO ||
          track->par->codec_id == AV_CODEC_ID_TRUEHD ||
          track->par->codec_id == AV_CODEC_ID_MPEGH_3D_AUDIO ||
+         (track->par->codec_id == AV_CODEC_ID_AAC && track->par->profile == AV_PROFILE_AAC_USAC) ||
          track->par->codec_tag == MKTAG('r','t','p',' ')) &&
         track->has_keyframes && track->has_keyframes < track->entry)
         mov_write_stss_tag(pb, track, MOV_SYNC_SAMPLE);