On windows IM aborted on assert once one
stoppped it. The reason is that we didn't
close the sockets on windows and therefore,
the listener thread wasn't able to finish.
This happened because we used close() call
for it. While on windows one should use
closesocket().
On other platfroms we have appropriate defines
for closesocket(), so this is the function which
should be used.


server-tools/instance-manager/listener.cc:
  close -> closesocket