Add --with-nsswitch to allow users to specify nsswitch.conf path or disable it. If --with-nsswitch=no but --with-ldap, order is LDAP, then sudoers. Fix --with-ldap-conf-file and --with-ldap-secret-file
which removes comments, leading/trailing whitespace and newlines. May want to rethink the use of sudo_parseln() for /etc/ldap.secret