Support ICECC_IGNORED_HOST to block usage of certain hosts

[alanbithell]

I sometimes find that a device on my network may start to misbehave and break my build with broken pipe errors, so I end up having to resort to using ICECC_PREFERRED_HOST to select a know good device to help speed up my compile jobs at least a little while I try to track down the user of that device.

Unfortunately this is happening more and more these days with multiple machines sitting behind a router with both machines running iceccd but port forwarding only reaching one of them.

If I had the ability to select multiple preferred hosts, I'd probably just lock that into my config and be done with it. Maybe it would be better to have a config for ICECC_IGNORED_HOSTS or similar.

[coolo]

ignored_hosts sounds like the more convincing user story.

[alanbithell]

Agreed ICECC_IGNORED_HOST sounds like a better option. Initially I was thinking of selecting a golden sample of machines I know and trust. But ignoring the bad actors would be better.