avformat/movenc: Write version 2 of audio atom if channels is not known

The version 1 needs the channel count and would divide by 0
Fixes: division by 0
Fixes: fpe_movenc.c_1108_1.ogg
Fixes: fpe_movenc.c_1108_2.ogg
Fixes: fpe_movenc.c_1108_3.wav

Found-by: #CHEN HONGXU# <HCHEN017@e.ntu.edu.sg>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
static int rtp_hinting_needed(const AVStream *st)
{
    /* Add hint tracks for each real audio and video stream */
    if (is_cover_image(st))
        return 0;
    return st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO ||
           st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO;
}

static int rtp_hinting_needed(const AVStream *st)
{
    /* Add hint tracks for each real audio and video stream */
    if (is_cover_image(st))
        return 0;
    return st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO ||
           st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO;
}
