Recover from a pacman lock left behind by a power cut

A machine switched off mid-update leaves /var/lib/pacman/db.lck behind. Nothing
removed it, so every subsequent run deferred on it - one power cut would have
stopped updates permanently and silently, which on an unattended machine is the
worst outcome there is.

A lock older than the current boot is provably abandoned: no process that could
hold it still exists. Those are now removed and the interrupted upgrade is
repeated, with pacman reinstalling anything caught half-written. A lock that is
merely unheld within the same boot stays untouched and is only reported, since
removing it could corrupt a live transaction; the boot-time test is what makes
the difference between a proof and a guess. A fuser check is kept alongside it
so a backwards clock jump cannot make a live lock look abandoned.

Documented what each layer can actually promise: suspend and normal shutdown
are blocked by the existing inhibitor, a hard power-off cannot be prevented by
anything, and snap-pac's pre/post snapshots remain the backstop.

po/cachy-auto-update.pot

@@ -257,3 +257,9 @@ msgstr ""
 
 msgid "The last run was stopped before it finished."
 msgstr ""
+
+msgid "Finishing an interrupted update"
+msgstr ""
+
+msgid "The last update was cut short, most likely because the machine was switched off. It is being finished now."
+msgstr ""

po/de.po

@@ -258,3 +258,9 @@ msgstr "Zurückgehalten: %s"
 
 msgid "The last run was stopped before it finished."
 msgstr "Der letzte Lauf wurde abgebrochen, bevor er fertig war."
+
+msgid "Finishing an interrupted update"
+msgstr "Abgebrochenes Update wird beendet"
+
+msgid "The last update was cut short, most likely because the machine was switched off. It is being finished now."
+msgstr "Das letzte Update wurde unterbrochen, vermutlich weil der Rechner ausgeschaltet wurde. Es wird jetzt zu Ende geführt."