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 mov_pcm_be_gt16(enum AVCodecID codec_id)
{
    return codec_id == AV_CODEC_ID_PCM_S24BE ||
           codec_id == AV_CODEC_ID_PCM_S32BE ||
           codec_id == AV_CODEC_ID_PCM_F32BE ||
           codec_id == AV_CODEC_ID_PCM_F64BE;
}

static int mov_pcm_be_gt16(enum AVCodecID codec_id)
{
    return codec_id == AV_CODEC_ID_PCM_S24BE ||
           codec_id == AV_CODEC_ID_PCM_S32BE ||
           codec_id == AV_CODEC_ID_PCM_F32BE ||
           codec_id == AV_CODEC_ID_PCM_F64BE;
}
