Function - Accept a lock hand-off.
[in send right] The port naming the lock set which represents the
[in scalar] The lock, represented by the lock set, that is the object
of the handoff operation.
The lock_handoff_accept function accepts a lock
hand-off from an anonymous sending thread. If the sending thread is
not waiting to hand-off the lock, the calling thread will block until
the lock handoff is completed. Only one thread may be waiting to
accept a lock handoff at any given time.
Another thread is already waiting for a hand-off of this lock.
The specified lock_set is invalid, or the lock_id is out of range.
The lock hand-off was successful.
The acquired lock has an unstable state.
The specified lock has been destroyed.
While blocked to wait for the sending thread to transfer the lock's ownership,
the calling thread was awoken by an unrelated event;
the lock's handoff state is cleared.