[config] Make PXE stack a compile-time option

For extremely tight space requirements and specific applications, it is
sometimes desirable to create gPXE images that cannot provide the PXE API
functionality to client programs. Add a configuration header option,
PXE_STACK, that can be removed to remove this stack. Also add PXE_MENU
to control the PXE boot menu, which most uses of gPXE do not need.

Signed-off-by: Marty Connor <mdc@etherboot.org>

src/config/config_romprefix.c

@@ -0,0 +1,24 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2, or (at
+ * your option) any later version.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <config/general.h>
+
+/** @file
+ *
+ * ROM prefix configuration options
+ *
+ */
+
+/*
+ * Provide UNDI loader if PXE stack is requested
+ *
+ */
+#ifdef PXE_STACK
+REQUIRE_OBJECT ( undiloader );
+#endif