fix stale autodaemonize cleanup

[CGamesPlay]

When shpool's daemon is killed, it may not be able to clean up its daemon. This will result in an error "daemonizing: launched daemon, but control socket never came up".

The fix is to detect a ConnectionRefused error and treat it as a dead daemon, unlinking the socket before attempting to start the daemon.

Test:

• shpool attach foo
• In a different terminal, killall -9 shpool
• shpool attach foo

[ethanpailes]

Thanks for finding and fixing this!

[ethanpailes]

Looks like there are some formatting issues that need fixing.

[CGamesPlay]

rebased and applied the cargo fmt changes