* Fixed a state machine bug in i8254.cpp, where re-enabling the timer could
  fail.
* Timer queues will no longer disable their latched timer source on
  cancel() if they are hosting the system clock update routine.
* Processes will now not be able to add more than one timer request to the
  Timer Trib timer queues in most cases.
* Implemented the code for timerTribC::cancelTimerQueueRequestObject().