acquire the acceptor cred and initator cred in two diffrent steps and
then query them for the information, this way, the code wont fail if
there are no keytab, but there is a credential cache.
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@17815 ec53bebd-3082-4978-b11e-865c3cabbd6b