QtNetwork: Handle FD_CLOSE on Windows

QtNetwork: Handle FD_CLOSE on Windows

We need to handle FD_CLOSE separately on Windows as this will be sent
only once. When we get FD_CLOSE we need to check if there is more data
available for reading. It there is this might indicate that there is
another FD_READ that we need to handle after the FD_CLOSE. So in this
case we will manually create another close event.

Task-number: QTBUG-19409
Task-number: QTBUG-25386
Change-Id: Ie19906bc3f64fb6a85a508a5ab12caac5d70ccdb
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>