ITS#9186 Add deferred ops statistics counters
This adds counters for deferred operations (per reason) as requested in pt. 2 of ITS#9186. It seemed most logical to make these per connection. Left them as "long" for consistency, since all other connection counters are "long", and if c_n_ops_received does not overflow, neither will any of these. Suggestions for better and clearer DESC of the attributes would be appreciated.