select wich key to encrypt the kdc rep with (in case of as-req), and
with the server info to select the session key type. The server key
the ticket is encrypted is based purely on the keys in the database.
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@3533 ec53bebd-3082-4978-b11e-865c3cabbd6b