include: Fix 64-bit sign extension in the MAKEWPARAM/LPARAM macros.

include/winuser.h

@@ -2078,9 +2078,9 @@ typedef struct tagMSG
 #define POINTSTOPOINT(pt, pts) { (pt).x = (pts).x; (pt).y = (pts).y; }
 #define POINTTOPOINTS(pt)      (MAKELONG((short)((pt).x), (short)((pt).y)))
 
-#define MAKELPARAM(low,high)   ((LPARAM)MAKELONG(low,high))
-#define MAKEWPARAM(low,high)   ((WPARAM)MAKELONG(low,high))
-#define MAKELRESULT(low,high)  ((LRESULT)MAKELONG(low,high))
+#define MAKELPARAM(low,high)   ((LPARAM)(DWORD)MAKELONG(low,high))
+#define MAKEWPARAM(low,high)   ((WPARAM)(DWORD)MAKELONG(low,high))
+#define MAKELRESULT(low,high)  ((LRESULT)(DWORD)MAKELONG(low,high))
 
 /* Cursors / Icons */