Turn on debugging override of idle time

'adb shell am idle-maintenance' has traditionally been used to force
the system to consider itself to be in an "idle" state.  Unfortunately
the new Job Manager hadn't yet been aware of this.  Rectify the situation.

Also fixes a bug in debug logging that would cause a system server
crash under certain race circumstances.

Change-Id: I8a29bd7757924f8e464865235c344233fc03d8c3