Infinite loops possible with multiple forwarding services on a system

[wentam]

If there are multiple services on a system forwarding inhibit events, an infinite loop of forwarding back and forth can be created. This situation can easily be produced by running 3 uinhibitd instances at the same time.

We might have enough identifying information to know that an inhibit is the 'same' event as one that already exists, and to ignore the event.

If not, a loop detection heuristic would be needed.

This isn't practically a big deal as I don't see realistic use-cases where such an infinite loop would be present, but we should still handle this for durability.

Probably try to build a unit test for the situation.