Added xxx_Unregister() functions to all common controls.

diff --git a/include/treeview.h b/include/treeview.h
index d48c5d4..756c16a 100644
--- a/include/treeview.h
+++ b/include/treeview.h
@@ -80,6 +80,7 @@
 } TREEVIEW_INFO;
 
 
-extern void TREEVIEW_Register (void);
+extern VOID TREEVIEW_Register (VOID);
+extern VOID TREEVIEW_Unregister (VOID);
 
 #endif  /* __WINE_TREEVIEW_H */