mac-sys-utils:  Add current_process()
mac-sys-utils:  Add async_wakeup unit
Genie, Pedestal:  Use reimplemented async wakeup
Pedestal:  Remove obsolete WakeUp unit
Merge branch 'async-wakeup'

Move asynchronous wakeup code out of Pedestal and into the mac-sys-utils
library.  Call mac::sys::request_async_wakeup() from I/O completion code
to schedule a wakeup of the process, and mac::sys::cancel_async_wakeup()
after WaitNextEvent() returns to signal that wakeup has completed.  It's
insufficient to merely call WakeUpProcess(), since that has no effect if
the target process is the current one.  Instead, we install a timer task
that calls WakeUpProcess() every 10ms until WaitNextEvent() returns (and
the task is removed).
Genie:  Remove short sleep hack in OTSocket read()

This isn't needed since the OT notifier requests an async wakeup.