Add TCP level timeout to LDAP services
    
    In some cases the TCP connection may hang with data sent because
    of network conditions, this may cause the socket to stall for much
    longer than the timeout intended.
    Set a TCP option to forcibly timeout a socket that sees its data not
    ACKed within the ldap_network_timeout seconds.
    
    Signed-off-by: Simo Sorce <simo@redhat.com>