freebsd-update upgrade failes if WITHOUT_IPX is used in src.conf

[Kevin Oberman]

If you use frebsd-up0date on a system that has WITHOUT_IPX= in src.conf,
you end up with a badly broken system as freebsd-update honors src.conf by
not installing liubipx.so, but fails to honor it by installing ifconfig
that required it leaving a system without a network. This is especially
messy if the system lacks sources to allow either  ifconfig to be re-built
or libipx to be built.

This should be fixed either by always having libipx installed by
freebsd-update or by having a binary NOT linked against libipx installed
when WITHOUT_IPX is used.

I also wonder how many similar cases might be present. For now,  my
recommendation is to not have anything in src.conf when using
freebsd-update.  As I will shhortly be moving this system back to stable, I
will not be continuing to use it on this system and will restore my
src.conf.

I'll try to submit a PR on this tomorrow.
-- 
R. Kevin Oberman, Network Engineer, Retired
E-mail: rkoberman at gmail.com