Do not crash client basedn discovery when SSF not met
ipa-client-install runs anonymous search in non-rootdse space which
may raise UNWILLING_TO_PERFORM error. This case was only covered for
BIND, but not for the actual LDAP queries.
https://fedorahosted.org/freeipa/ticket/4459
Reviewed-By: Petr Viktorin <pviktori@redhat.com>