[gPXE] Problems with gPXE, UNDI and VirtualBox

[Lars Kellogg-Stedman]

> #define PXENV_STATUS_UNDI_CANNOT_INITIALIZE_NIC 0x63
>
> Are you sure pxelinux.0 works in exactly the same VM?

I am only testing with a single VM.  It's netbooting from a server
running dnsmasq; the only change is:

  dhcp-boot=undionly.kpxe

vs:

  dhcp-boot=pxelinux.0

Since VirtualBox is broken on the trunk in any case, I'm inclined to
just ignore the problem and pick up KVM instead.