[mythtv] MythShutdownWakeupTime database key

[Matthew Wire]

When is this key set?
MythTV uses it to check whether it was automatically started or not but
I cannot see anywhere where it would be set - only two references in the
entire code, once in mythshutdown and once in scheduler.

MythShutdownNextScheduled is used to set the wakeuptime but this is not
copied to MythShutdownWakeupTime or anything as I thought it might.

Cheers,
Matthew