build can't find des.h

[Harald Barth]

> Should rxkad be getting built when I only have krb4, or should the rxkad stuff 
> not get called?


Rxkad should be built if you have either krb4 or krb5 or both. You
will sleep better with krb5. Arlad should build even if you have none
of the krb* stuff (and then it just provides AFS without auth). That
it fails to link is a bug which has not been noted as noone has tried
that combination for a long time.

Harald.