dispatch_check_rlimit_and_warn: get_connections() changed semantics

It makes no sense to report the number of connections accepted since the
start of the program, so just don't do it.  Besides that, we shouldn't
be hitting rlimits any more, since we're doing much better in keeping
the amount of connections low.
dispatch: expose both accepted and closed connections

Report on connections and disconnects so we can calculate the amount of
actual connected clients (sort of).