struct LockForWakeResult

Attempt to lock the set of threads needed for a BrwLock wake operation. If

the first thread to wake is a writer, the set consists of just this thread.

If the first thread to wake is a reader, then the set to wake is all of the

readers we encounter until we hit another writer, or run out of threads to

wake.

On success, the list of threads to wake is returned with each thread

locked, and with each thread prepared to unblock as if Dequeue had been

called (blocked_status has been set to OK, and blocking_wait_queue has been

cleared).

On failure, no list is returned, and all threads will be unlocked and

waiting in the collection.