avtools: move media_type_string() from avprobe to cmdutils.

It will be useful outside of avprobe.

avprobe.c

@@ -526,20 +526,6 @@ static char *tag_string(char *buf, int buf_size, int tag)
     return buf;
 }
 
-
-
-static const char *media_type_string(enum AVMediaType media_type)
-{
-    switch (media_type) {
-    case AVMEDIA_TYPE_VIDEO:      return "video";
-    case AVMEDIA_TYPE_AUDIO:      return "audio";
-    case AVMEDIA_TYPE_DATA:       return "data";
-    case AVMEDIA_TYPE_SUBTITLE:   return "subtitle";
-    case AVMEDIA_TYPE_ATTACHMENT: return "attachment";
-    default:                      return "unknown";
-    }
-}
-
 static void show_packet(AVFormatContext *fmt_ctx, AVPacket *pkt)
 {
     char val_str[128];

cmdutils.c

@@ -1553,3 +1553,15 @@ void *grow_array(void *array, int elem_size, int *size, int new_size)
     }
     return array;
 }
+
+const char *media_type_string(enum AVMediaType media_type)
+{
+    switch (media_type) {
+    case AVMEDIA_TYPE_VIDEO:      return "video";
+    case AVMEDIA_TYPE_AUDIO:      return "audio";
+    case AVMEDIA_TYPE_DATA:       return "data";
+    case AVMEDIA_TYPE_SUBTITLE:   return "subtitle";
+    case AVMEDIA_TYPE_ATTACHMENT: return "attachment";
+    default:                      return "unknown";
+    }
+}

cmdutils.h

@@ -514,6 +514,11 @@ FILE *get_preset_file(char *filename, size_t filename_size,
  */
 void *grow_array(void *array, int elem_size, int *size, int new_size);
 
+/**
+ * Get a string describing a media type.
+ */
+const char *media_type_string(enum AVMediaType media_type);
+
 #define GROW_ARRAY(array, nb_elems)\
     array = grow_array(array, sizeof(*array), &nb_elems, nb_elems + 1)