Only display ACPI bootmenu key if ACPI is present

[Kevin Lo]

John Baldwin wrote:
> This patch changes the Forth code for the Beastie menu to only display the
> menu option to enable or disable ACPI if the loader detects ACPI.  This avoids
> displaying a menu item prompting to enable ACPI if the BIOS doesn't actually
> include ACPI.  Any objections?

I have no objection. This patch makes sense to me.

	Kevin