Kerberos can now deal with multi-homed clients.

Kerberos obtains a network address for the local host from the routing
tables and uses it consistently for all Kerberos transactions. This ensures
that packets only leave the *authenticated* interface. Clients who open
and use their own sockets for encrypted or authenticated correspondance
to kerberos services should bind their sockets to the same address as that
used by kerberos. krb_get_local_addr() and krb_bind_local_addr() allow
clients to obtain the local address or bind a socket to the local address
used by Kerberos respectively.

Reviewed by: Mark Murray <markm>, Garrett Wollman <wollman>
Obtained from: concept by Dieter Dworkin Muller <dworkin@village.org>