QtNetwork: Better detection of connection failures on Windows

QtNetwork: Better detection of connection failures on Windows

If the error code from WSAConnect is WSAEWOULDBLOCK, then the
operation proceeds but the outcome is not known at that time. We then
check SO_ERROR's value to detect errors. But if that call returns 0
this could indicate that the value is still not know. In this case
we try one more time to increase the chance of getting the correct
value.

This fixed the tst_QNetworkReply::getFromUnreachableIp auto test
on Windows.

Change-Id: I25008aca062b2f823e3d93ebb0ae456d7e4a6ecc
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>