Evan Hunt authored Feb 22, 2019 and Ondřej Surý committed Apr 25, 2019

in the "refactor tcpquota and pipeline refs" commit, the counting
of active interfaces was tightened in such a way that named could
fail to listen on an interface if there were more interfaces than
tcp-clients. when checking the quota to start accepting on an
interface, if the number of active clients was above zero, then
it was presumed that some other client was able to handle accepting
new connections. this, however, ignored the fact that the current client
could be included in that count, so if the quota was already exceeded
before all the interfaces were listening, some interfaces would never
listen.

we now check whether the current client has been marked active; if so,
then the number of active clients on the interface must be greater
than 1, not 0.

(cherry picked from commit 71fead4c3e03b178d6e6e3ff7592b45cf5f94069)
(cherry picked from commit 78565872)