[krbdev.mit.edu #6405] fixing several bugs relating to the migrate mkey project using a LDAP KDB

[william.fiveash@sun.com via RT]

While testing the migrate mkey functionality when a LDAP KDB is in use I
noticed these commands failed:
kdb5_util add_mkey
kdb5_util update_princ_encryption -f
kdb5_util -x "binddn=cn=adm-service,dc=zone,dc=net" purge_mkeys -f

I have a small patch which fixes these issues and also removes some dead
code that was introduced by the migrate mkey project.