avformat/mov: don't unconditionally set all audio packets in fragments as key frames

Some audio codecs, like TrueHD, have non key frames.

Signed-off-by: James Almer <jamrial@gmail.com>
(cherry picked from commit 8ddbc26ded)

libavformat/mov.c

@@ -5843,9 +5843,6 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
             pts = AV_NOPTS_VALUE;
         }
 
-        if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO)
-            keyframe = 1;
-        else
         keyframe =
                 !(sample_flags & (MOV_FRAG_SAMPLE_FLAG_IS_NON_SYNC |
                                   MOV_FRAG_SAMPLE_FLAG_DEPENDS_YES));