[gPXE] hopefully user error trying to chainload menu.c32

[Miller, Shao]

Good day J. C.,

How about if boot.php returns:

#!gpxe
set 210:string http://pxe.influent.local/pxe/
chain ${210:string}menu.c32 menu.php

Does that work any better for you?  210 is a DHCP option which we see
here is manually set in the script itself, which tells Syslinux about a
path to use for relative filepaths, such as menu.php, above.  If it
doesn't work, call again.

- Shao Miller