wavpack: use enum tag_type

Don't store tag type values in a plain integer, use the proper enum.

src/decoder/wavpack_plugin.c

@@ -31,7 +31,7 @@
 
 static struct {
 	const char *name;
-	int type;
+	enum tag_type type;
 } tagtypes[] = {
 	{ "artist", TAG_ITEM_ARTIST },
 	{ "album", TAG_ITEM_ALBUM },