include: The PSDK headers don't define WM_SYSTIMER so we shouldn't either.

dlls/user/tests/msg.c

@@ -42,6 +42,10 @@
 
 #define SW_NORMALNA	        0xCC    /* undoc. flag in MinMaximize */
 
+#ifndef WM_SYSTIMER
+#define WM_SYSTIMER	    0x0118
+#endif
+
 #define WND_PARENT_ID		1
 #define WND_POPUP_ID		2
 #define WND_CHILD_ID		3

dlls/user/user_private.h

@@ -81,6 +81,8 @@ static inline HLOCAL16 LOCAL_Free( HANDLE16 ds, HLOCAL16 handle )
 #define GET_WORD(ptr)  (*(const WORD *)(ptr))
 #define GET_DWORD(ptr) (*(const DWORD *)(ptr))
 
+#define WM_SYSTIMER	    0x0118
+
 /* internal messages codes */
 enum wine_internal_message
 {

include/winuser.h

@@ -1105,7 +1105,6 @@ BOOL        WINAPI SetSysColors(INT,const INT*,const COLORREF*);
 #define WM_COMMAND          0x0111
 #define WM_SYSCOMMAND       0x0112
 #define WM_TIMER	    0x0113
-#define WM_SYSTIMER	    0x0118
 
   /* scroll messages */
 #define WM_HSCROLL          0x0114