This function converts 16-bit unsigned integers from network byte
    order to host byte order.
    Data bytes transmitted over the network are expected to be
    in network byte order. Some hosts, like OpenVMS, have an
    internal data representation format that is different from the
    network byte order; this is called the host byte order. Network
    byte order places the byte with the most significant bits at
    lower addresses, but OpenVMS host byte order places the most
    significant bits at the highest address.
    This function can be used to convert port numbers returned by
    getservent() from network byte order to host byte order.