[gnet] Asynchronous connections fail on windows.

[martyn 2 russell bt com]

If I use the example you provide as below, no connection is ever
established. I have found this to be the case in my application to.
./echoclient.exe --async 132.146.163.10 80

Also, If I test the hfetch example with the same server, on the same port,
the web page is returned to me with no problems (this is not asynchronous).

These all work fine on Linux.

Regards,
Martyn