resizes the completion queue (CQ)
to have at least
must be at least the number of unpolled entries in the CQ
is a valid value less than the current CQ size,
may not do anything, since this function is only guaranteed to resize
the CQ to a size at least as big as the requested size.
returns 0 on success, or the value of errno on failure (which indicates the failure reason).
may assign a CQ size greater than or equal to the requested size.
The cqe member of
will be updated to the actual size.