Remove dependency on obsolete nit_data_ data segment

[Eric Swenson]

The standard Mutlics mail system (>sss>bound_mail_system_) has a mechanism to check for the existence of the Inter-System Mailer (ISM), which, historically was only shipped as a separately priced product -- the TCP/IP software. The mechanism used is a linkage fault protected attempt to access nit_data_$local_host. This segment is not provided with the standard system, but only with the TCP/IP software. However, nit_data_ is now obsolete in the TCP/IP software and will not be included when the networking software is included in the next release of Multics (MR12.9).

Whereas in the MIT/Honeywell TCP/IP software, there were three places where the local host name was defined (network_site_data_, network_local_data_, and nit_data_), the networking software to be included in MR12.9 will only use network_local_data_ and its subroutine interface, network_local_info_. The other two data segments were older versions and in various stages of being made obsolete. The current networking stack will no longer include network_site_data_ and nit_data_, and all references to network_local_data_ are encapsulated into the network_local_info_ subroutine.

This MCR proposes to update the standard mail system to use network_local_info_$get_host_name rather than nit_data_$local_host in both the ISM-presence check, as well as the code in mlsys_nit_interface_ that attempts to determine the local system host name.

[Eric Swenson]

​https://s3.amazonaws.com/eswenson-multics/public/mcrs/MCR10169.pdf

[Eric Swenson]

Fixed with MR12.9-1044.

[Eric Swenson]

Duplicate of 402.