Ticket #47359 - new ldap connections can block ldaps and ldapi connections
    
    https://fedorahosted.org/389/ticket/47359
    Reviewed by: lkrispen
    Branch: master
    Fix Description: description
    In the polling thread, first process all of the new connection requests from
    the listening sockets, then process any new operation read requests
    The listener_idxs keeps track of the index of the active listeners in the
    poll fd array, and keeps a pointer to the listenfd object for that
    listener.  This allows us to very quickly scan through the poll fd array
    and find the ready listeners.  The work of scanning through the array
    and handling the new connection requests has been moved to a new function
    handle_listeners().
    Platforms tested: RHEL6 x86_64
    Flag Day: no
    Doc impact: no
    (cherry picked from commit 115ab1d9a3f026e8523b91bf62245a25454a3e8a)