PrepareFor{Sleep,Shutdown} (false) signals not emitted

Per

  http://www.freedesktop.org/wiki/Software/systemd/inhibit

"PrepareForShutdown(false) may be subscribed to by applications which want to be notified about system resume events. Note that this will only be sent out for suspend/resume cycles done via logind, i.e. generally only for high-level user-induced suspend cycles, and not automatic, low-level kernel induced ones which might exist on certain devices with more aggressive power management. "

(I think it means s/Shutdown/Sleep in the first sentence)

Our systemd has a patch 0016-Add-poweroff-reboot-suspend-hibernate-fallback.patch which calls the executables from pm-utils in the case that the systemd D-Bus API isn't available (which is the case for us). Usually, logind calls shutdown/suspend/... methods via systemd jobs. In our case, since we call these executables directly, the jobs aren't used and so the standard systemd Job* signals aren't sent. It's these signals that logind listens for to know when to emit the PrepareFor{Sleep,Shutdown} (false) signals.

I attach a strawman patch (diff of a diff - look at it after applying) which explicitly sends the signal and does some other needed cleanups (see bus_message_filter for the call site for where the signal is usually sent). Let me know what you think.