Moved undocumented functions out of the exported commctrl.h.

diff --git a/dlls/comctl32/treeview.c b/dlls/comctl32/treeview.c
index 22cd0c8..fbf75ac 100644
--- a/dlls/comctl32/treeview.c
+++ b/dlls/comctl32/treeview.c
@@ -1815,7 +1815,7 @@
 
 
 static INT CALLBACK
-TREEVIEW_ResetTextWidth(LPVOID pItem, DWORD unused)
+TREEVIEW_ResetTextWidth(LPVOID pItem, LPVOID unused)
 {
     (void)unused;