Add define for undocumented status bar message SB_SETBORDERS.

include/commctrl.h

diff --git a/include/commctrl.h b/include/commctrl.h
index ea244d5..c18dc1d 100644
--- a/include/commctrl.h
+++ b/include/commctrl.h
@@ -271,6 +271,7 @@
 #define SB_GETTEXTLENGTHW	(WM_USER+12)
 #define SB_GETTEXTLENGTH	WINELIB_NAME_AW(SB_GETTEXTLENGTH)
 #define SB_SETPARTS		(WM_USER+4)
+#define SB_SETBORDERS		(WM_USER+5)
 #define SB_GETPARTS		(WM_USER+6)
 #define SB_GETBORDERS		(WM_USER+7)
 #define SB_SETMINHEIGHT		(WM_USER+8)