... also (C)ompleted bans.

The previous code made a lot of sense in light of the performance issue
due to too many bans, but would not work to prune a long ban list due to
(R)equest bans at the tail, as in this example:

Present bans:
1607346873.538879 354304 C
1607346873.532313     0 C
... lots of (C)ompleted bans
1607083561.980118     0 -  req.http.Host ~ foo
1607083561.972629    15 C

The documentation does not mention the previous behavior (that only
"active" bans are being counted), so this changes aligns code to
documentation.