remuxing .opus files to .webm codec->delay must be copied too

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

ffmpeg.c

@@ -2375,6 +2375,7 @@ static int transcode_init(void)
                 codec->frame_size         = icodec->frame_size;
                 codec->audio_service_type = icodec->audio_service_type;
                 codec->block_align        = icodec->block_align;
+                codec->delay              = icodec->delay;
                 if((codec->block_align == 1 || codec->block_align == 1152 || codec->block_align == 576) && codec->codec_id == AV_CODEC_ID_MP3)
                     codec->block_align= 0;
                 if(codec->codec_id == AV_CODEC_ID_AC3)