QLocalSocket/Win: remove dead code in disconnectFromServer()

The _q_pipeClosed() slot unconditionally removes the pipeWriter just
before closing the pipe. Thus, if we have an invalid handle here,
the pipe writer has already been destroyed anyway.

Change-Id: I57463d8464afe6141c21a63851a56ebddabd3f13
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>

src/network/socket/qlocalsocket_win.cpp

@@ -407,14 +407,6 @@ void QLocalSocket::disconnectFromServer()
 {
     Q_D(QLocalSocket);
 
-    // Are we still connected?
-    if (!isValid()) {
-        // If we have unwritten data, the pipeWriter is still present.
-        // It must be destroyed before close() to prevent an infinite loop.
-        delete d->pipeWriter;
-        d->pipeWriter = 0;
-    }
-
     flush();
     if (bytesToWrite() != 0) {
         d->state = QLocalSocket::ClosingState;