By copying this code I got bad comments in reviewboard... Better fix the original.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@215023 65c4cc65-6c06-0410-ace0-fbb531ad65f3

funcs/func_volume.c

@@ -68,7 +68,7 @@ static void destroy_callback(void *data)
 
 	/* Destroy the audiohook, and destroy ourselves */
 	ast_audiohook_destroy(&vi->audiohook);
-	free(vi);
+	ast_free(vi);
 
 	return;
 }