Disable late suspend when the device is shutting down

Shutdown is signalled by shutdown_ind dbus signal from dsme. After
receiving it, mce retains a wakelock if auto suspend is enabled
and thus blocks entry to late suspend.
Allow compiling mce without enabling wakelock support

All wakelock manipulation calls were not inside
  #ifdef ENABLE_WAKELOCKS ... #endif
blocks
Merge pull request #25 from spiiroin/no_suspend_on_shutdown

Disable late suspend when the device is shutting down