gsm: convert to new channel layout API

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/gsmdec.c

@@ -79,8 +79,7 @@ static int gsm_read_header(AVFormatContext *s)
 
     st->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
     st->codecpar->codec_id    = s->iformat->raw_codec_id;
-    st->codecpar->channels    = 1;
-    st->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
+    st->codecpar->ch_layout   = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
     st->codecpar->sample_rate = c->sample_rate;
     st->codecpar->bit_rate    = GSM_BLOCK_SIZE * 8 * c->sample_rate / GSM_BLOCK_SAMPLES;