Milter-greylist

> The new patch breaks our sync mechanism. The sync listener thread does
> not start before a client connects to the server.
> 
Already first connection from the client at the connect phase
(first call back form mlfi_main) will start the sync listener.
All the other connections will be blocked on the new mutex
which got introduced. There is no any difference with the situation
before.

On the other hand it was neither guaranteed before the patch
that the sync listener did any kind of useful thing before client
connections came in, since it is not a high priority
real-time thread.

Bests,
Attila