lavf: use designated initialisers for all (de)muxers.

It's more readable and less prone to breakage.

libavformat/vocdec.c

@@ -157,11 +157,11 @@ static int voc_read_packet(AVFormatContext *s, AVPacket *pkt)
 }
 
 AVInputFormat ff_voc_demuxer = {
-    "voc",
-    NULL_IF_CONFIG_SMALL("Creative Voice file format"),
-    sizeof(VocDecContext),
-    voc_probe,
-    voc_read_header,
-    voc_read_packet,
+    .name           = "voc",
+    .long_name      = NULL_IF_CONFIG_SMALL("Creative Voice file format"),
+    .priv_data_size = sizeof(VocDecContext),
+    .read_probe     = voc_probe,
+    .read_header    = voc_read_header,
+    .read_packet    = voc_read_packet,
     .codec_tag=(const AVCodecTag* const []){ff_voc_codec_tags, 0},
 };