Bug 504803 - Allow nsslapd-*-logmaxdiskspace to be set to -1 in UI
    
    It is not currently possible to set the total log maximum disk
    space parameter to "-1" in the Console for the access log or the
    error log.  This is a valid parameter in the server that means
    "unlimited".
    
    The problem is that the validation method wants to ensure that the
    max disk space is not less than the size configured for a single log
    file.  We should not perform this check if the max disk space is
    unlimited (-1).