comctl32: Constify some variables (2 of 12)

[Andrew Talbot]

Changelog:
    comctl32: Constify some variables.

diff -urN a/dlls/comctl32/comctl32undoc.c b/dlls/comctl32/comctl32undoc.c
--- a/dlls/comctl32/comctl32undoc.c	2007-03-23 14:23:40.000000000 +0000
+++ b/dlls/comctl32/comctl32undoc.c	2007-03-31 14:39:02.000000000 +0100
@@ -1019,7 +1019,7 @@
  * DoNotify [Internal]
  */
 
-static LRESULT DoNotify (LPNOTIFYDATA lpNotify, UINT uCode, LPNMHDR lpHdr)
+static LRESULT DoNotify (const NOTIFYDATA *lpNotify, UINT uCode, LPNMHDR lpHdr)
 {
     NMHDR nmhdr;
     LPNMHDR lpNmh = NULL;