Update to Freeciv server 8e2801d583

Freeciv commit message:
Fix all can_unit_do_activity_targeted_at() calls.

A call to is_action_enabled_unit_on_*() replaced the hard coded checks in
can_unit_do_activity_targeted_at() for each activity that became action
enabler controlled. is_action_enabled_unit_on_*() cares about distance
between actor an target. This caused can_unit_do_activity_targeted_at() to
lose it's ability to speculate about the actor unit's tile for action enabler
controlled activities.

Actor unit tile speculation with can_unit_do_activity_targeted_at() is only
used in the auto settler code of ai/tex, ai/threaded and
advisors/autosettlers. Its remaining users can't be ported to use speculative
action enabler evaluation until all the activities they may consider have
corresponding actions.

Introduce auto_settlers_speculate_can_act_at(). It calls the correct
speculative evaluation function based on if the specified activity has a
corresponding action or not: can_unit_do_activity_targeted_at() when no
corresponding action is found. action_speculate_unit_on_*() when it is.

Port remaining actor position speculating can_unit_do_activity_targeted_at()
calls to auto_settlers_speculate_can_act_at(). Assert that calls to
can_unit_do_activity_targeted_at() for action enabler controlled activities
don't speculate about actor unit position.

See hrm Bug #758450

freeciv/version.txt

@@ -1,7 +1,7 @@
 # The Git SHA hash for the commit to checkout from
 # https://github.com/freeciv/freeciv
 
-FCREV=a063d701e589fb2a50e3915f74bcc6f62c2721a3
+FCREV=8e2801d583e1aaaee2bfaf3229e2ba233b518ff3
 
 ORIGCAPSTR="+Freeciv.Devel-3.1-2018.Jun.06"