Make function get_channel_name() static: It is only used in audioconvert.c.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@22114 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/audioconvert.c

@@ -79,7 +79,7 @@ static const char* const channel_names[]={
     [30] = "DR",
 };
 
-const char *get_channel_name(int channel_id)
+static const char *get_channel_name(int channel_id)
 {
     if (channel_id<0 || channel_id>=FF_ARRAY_ELEMS(channel_names))
         return NULL;