Bug 640854 - changelog db: _cl5WriteOperation: failed to
    write entry; db error - 22 Invalid argument
    
    https://bugzilla.redhat.com/show_bug.cgi?id=640854
    
    Description: DBENV open flags is used to determine the DB_OPEN mode
    whether to set DB_AUTO_COMMIT or not.  The info was eliminated in
    the change made for "Bug 633168 - Share backend dbEnv with the
    replication changelog".
    
    This patch picks up the backend dbenv openflags and uses it for
    the changelog DB_OPEN.