(update_running): New.

(update_running): New.
(update_run): Set it.

Replace incorrect uses of update_pending by update_running, fixing
buggy behavior while the update was trying to gain control:
(sct_do_upd_mob, shp_do_upd_mob, lnd_do_upd_mob, pln_do_upd_mob):
MOB_ACCESS mobility update was skipped.
(telegram_is_new): Fix recognition of new telegrams by timestamp.
(wu): Bulletins got misfiled as production reports.
(shp_nav): Sail path got ignored.
(setrel): Declaration of war failed silently with SLOW_WAR enabled.
Messages got suppressed.
(PR, mpr): Messages got misdirected to bulletins.