kinit: add KDB keytab support
This implements
http://k5wiki.kerberos.org/Projects/What_does_God_need_with_a_password.
If the KDB keytab is selected by command line options, then kinit will
register the KDB keytab and open the database. This permits an
administrator to obtain tickets as a user without knowing that user's
password.
As a result kinit links against libkadm5srv and libkdb5. Discussion is
ongoing about whether this is desirable or about whether two versions
of kinit are required.
ticket: 6779
git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@24316
dc483132-0cff-0310-8789-
dd5450dbe970