Previously, this code was being confused by the re-use/overloading of
existing keywords in the ifcpu64.c module and not producing any menu
entries. Now, explicitly parse the new options and pick out just the
64-bit menus as they're a strict superset of the menus in isolinux.
This may enable some more issues, e.g. people trying to load a 64-bit
kernel on a 32-bit system, but until we get some auto-detection of CPU
in grub there's not much we can do about that. Let's get *something*
working at least.
Steve McIntyre