[HEADS UP] mulitboot 2 support for x86 bootloaders

[manu%netbsd.org@localhost (Emmanuel Dreyfus)]

I committed multiboot 2 support for x86 bootloaders. This enable booting
Xen from a EFI system.

That this also require a kernel change, otherwise the NetBSD dom0
crashes at startup because it fails to detect ACPI.
src/sys/arch/x86/acpi/acpi_machdep.c 1.26-1.28

For now, the bootloader prefer multiboot 2 over multiboot 1 if the
kernel has both capacities. It we discover issues there, we could add a
way to specify multiboot 1 preference in boot.cfg.

-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu%netbsd.org@localhost