[bug#39136] My endlessh patch series

[Joshua Branson]

So I've been working on this endlessh service for a while.  I believe
it could be better, but perfectionist can only do one thing perfectly:
nothing.  So I've submitted the above patch series.  Let me know if it
needs more work.

At the moment, I believe that endlessh runs as root.  It would be nice
to let it run as user nobody or something like that.

The endlessh systemd file provides an example of how to do that:

https://github.com/skeeto/endlessh/blob/master/util/endlessh.service

## If you want Endlessh to bind on ports < 1024
## 1) run: 
##     setcap 'cap_net_bind_service=+ep' /usr/local/bin/endlessh
## 2) uncomment following line
#AmbientCapabilities=CAP_NET_BIND_SERVICE
## 3) comment following line
PrivateUsers=true

Though setcap 'cap_net_bind_service=+ep' is linux specific.  And I'm
not certain if guix has a method for running setcap on items in the
store.

Those are just some relevant thoughts for improving the service!

Thanks!