Use min/max instead of MIN/MAX.

diff --git a/programs/winhelp/macro.c b/programs/winhelp/macro.c
index 82fd5a2..a7f6e26 100644
--- a/programs/winhelp/macro.c
+++ b/programs/winhelp/macro.c
@@ -161,7 +161,7 @@
 
   button->wParam = WH_FIRST_BUTTON;
   for (b = &win->first_button; *b; b = &(*b)->next)
-    button->wParam = MAX(button->wParam, (*b)->wParam + 1);
+    button->wParam = max(button->wParam, (*b)->wParam + 1);
   *b = button;
 
   SendMessage(win->hMainWnd, WM_USER, 0, 0);