Add exit request support for external helper to be able to control daemons' states
[ ] support exit while connected
[ ] support exit at client side while attempting to connect
[ ] support exit for server process
[ ] fd server exit request support (check SHM)
server and client connecting processes can receive ordinary signals and exit; but it can be a challenge to get their PID
client may update their SHM status pid so that helper can find them; but as their process_num is unkown at this time it is inconsistent to use the available fields;
connecting client may check SHM field that indicates exit request, at process_num 0
server listening process may check exit request at SHM index 0 process_num 0; should receive a SIGHUP in order to exit though as it waits on accept indefinitely; need to check that connected processes safely ignore it
Add exit request support for external helper to be able to control daemons' states
server and client connecting processes can receive ordinary signals and exit; but it can be a challenge to get their PID