[syslinux] syslinux.efi pxeboot across multiple subnets

[Jason Matthews]

>I played around with the udp4_cb function and it looked like it was coming
back with token->Status == 512, which (if I read the spec right) isn't a
valid value. I'm not sure what is coming through on that. I changed the if
to if (token->Event) { cb_status = 0; }

Looks like the same thing with tcp.c. After I changed that callback,
everything went through and I go into the OS install.

But, if I go back to 1 subnet after those changes, it errors out with
Invalid Parameter when attempting to send the first packet.

(Sorry for the top posting.)