reqOid - the id of the reply for which a waiters is to be found
The LockReq identifying the matched waiter.
Excluded in public API Reference.
Gets a suitable waiter for the reply identified by reqOid.
The waiter could be one waiting specifically for this reqOid
(specific waiter) or one waiting for any reqOid (generic waiter).
Preference given to specific waiter. Selected waiter is removed
from appropriate waiter list and returned.