Add new functions that will be used in the next patch. The new behavior
is to search for particular keytab entries in a specified order:
root/<fqdn>@<REALM>
nfs/<fqdn>@<REALM>
host/<fqdn>@<REALM>
root/<any-name>@<REALM>
nfs/<any-name>@<REALM>
host/<any-name>@<REALM>
Signed-off-by: Kevin Coffman <kwc@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>