sect: Keep work percentage without civilians at 100%

sect: Keep work percentage without civilians at 100%

We maintain a few sector invariants in sct_prewrite().  Since the
update bypasses sct_prewrite(), it needs to maintain them itself.  The
two should be consistent.

sct_prewrite() resets work percentage of owned sectors to 100% when
there are no civilians.  The update's populace() resets it for unowned
sectors as well, if they have military.

Change sct_prewrite() to reset sct_work = 100 regardless of owner.
Also change sct_oninit() to initialize sct_work = 100, so it doesn't
change on first write.  Update tests/smoke/fairland.xdump for the same
reason.

The massive test output differences are all due to sct_work.

Inconsistencies with the update remain.  They will be fixed next.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>