save the old password if either the authentication or the authorisation response is NEW_AUTHTOK_REQD (c89c41b from 0.9)

git-svn-id: http://arthurdejong.org/svn/nss-pam-ldapd/nss-pam-ldapd-0.8@1939 ef36b2f9-881f-0410-afb5-c4e39611909c