[syslinux] Problems with NBP chaining

[Roy Badami]

   We'll find out just how well the Intel Boot Agent copes with unloading
   PXE then reloading it...  Wouldn't surprize me too much if it just
   doesn't work... Also wondering whether the cached DHCP/PXE responses
   will be retained... :-/

Oh, of course, we're only closing the UDP API, not doing anything more
drastic, so that really should be safe.  Still getting the hang of
how this all fits together...

	-roy