matroskadec: move ARRAY_SIZE() macro at top of the file

Originally committed as revision 13633 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/matroskadec.c

@@ -172,6 +172,8 @@ typedef struct MatroskaDemuxContext {
     AVStream *skip_to_stream;
 } MatroskaDemuxContext;
 
+#define ARRAY_SIZE(x)  (sizeof(x)/sizeof(*x))
+
 /*
  * The first few functions handle EBML file parsing. The rest
  * is the document interpretation. Matroska really just is a
@@ -2308,8 +2310,6 @@ matroska_parse_chapters(AVFormatContext *s)
     return res;
 }
 
-#define ARRAY_SIZE(x)  (sizeof(x)/sizeof(*x))
-
 static int
 matroska_aac_profile (char *codec_id)
 {