Freeciv

It's possible to specify that an extra like Pollution can be removed by pillaging, and that causes the online help and menu sensitivity to make the pillage action possible, but when you choose it, nothing happens.

This is because get_preferred_pillage() doesn't consider every extra_cause, only extras caused by player activity and those with no cause; and this function acts as a gatekeeper to all pillaging.

Now that we have fine-grained rmcauses, there doesn't seem to be a good reason to restrict the pillage rmcause to "infrastructure" type extras.

(I bumped into this while testing another fix. I'm fixing this on 2.6 because that's where I am working, but a ruleset which wanted to actually take advange of this would need both an updated client and server, to stop the client self-censoring its ability to do the pillage.)