1.9.4: TCP queries when some threads are full

[Havard Eidnes]

> That is an interesting find, well done and thanks for sharing!
>
> Looking at the patch I wanted to read about comm_point_start_listening()
> and found some documentation at
> https://nlnetlabs.nl/documentation/unbound/doxygen/netevent_8h.html
> which states:
> ```
> msec    timeout in milliseconds, or -1 for no (change to the) timeout.
> So seconds*1000.
> ```

Hum, you're better than me to search the documentation; I didn't
even think to look there...

And on second reading, it looks like "-1 for no change to the timeout"
is correct; assuming libevent doesn't itself mess with the bits in the
"event" structure it gets passed.

So while the new code isn't wrong per se, it may not be fixing what I
thought it would. :(

Regards,

- Håvard