Freeciv

When considering (with limited knowledge) the possibility of airlifting from/to foreign city, the functions action_hard_reqs_actor in actions.c and test_unit_can_airlift_to in unit.c return uncertain results due to unknown airlift counter even if airlift_from/to_always_enabled is set. This has actually few effect since client allows maybe-possible actions.

Headscratches note: how does it check presence of non-mutual ally units in a foreign city? I tested it in v.3.1 and the unit stays in source city without any note, so some check is performed but idk where, seems like definitely not in do_airlime.