There are use vars in openldap-2.0.25-r2 that are not in use.desc. They are ldap-berkdb, ldap-gdbm.
those are undocumented and wrong USE flag. ldap-berkdb should be berkdb and ldap-gdbm simply gdbm. However .. indeed, there are several USE flags not specified in use.desc An example is net-www/mozilla. Why aren't those flag documented ?
seemant, you forgot to change the compile use vars to berkdb and gdbm
sorry about that.