Fix null pointer dereference and assertion failure conditions that
could cause a denial of service.

https://github.com/krb5/krb5/commit/1a28d1da0ceef87a9f1dc85d840aef4601e6fa4e
Commit By: tlyu
Revision: 25369
Changed Files:
U   branches/krb5-1-9/src/plugins/kdb/db2/lockout.c
U   branches/krb5-1-9/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c
U   branches/krb5-1-9/src/plugins/kdb/ldap/libkdb_ldap/lockout.c