QLocalSocket: do not emit aboutToClose() twice

This signal is emitted by the QIODevice itself, so we don't have to
forward it from the internal socket.

Change-Id: I85745f36d7a27d92f339a9184de3b6e5d46f6f34
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
(cherry picked from commit 21f3ff65b8df777b5726a68b09bbee39f1a893ec)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/network/socket/qlocalsocket_tcp.cpp

@@ -68,7 +68,6 @@ void QLocalSocketPrivate::setSocket(QLocalUnixSocket* socket)
 
     Q_Q(QLocalSocket);
     // QIODevice signals
-    q->connect(tcpSocket, SIGNAL(aboutToClose()), q, SIGNAL(aboutToClose()));
     q->connect(tcpSocket, SIGNAL(bytesWritten(qint64)),
                q, SIGNAL(bytesWritten(qint64)));
     q->connect(tcpSocket, SIGNAL(readyRead()), q, SIGNAL(readyRead()));

src/network/socket/qlocalsocket_unix.cpp

@@ -72,7 +72,6 @@ void QLocalSocketPrivate::init()
 {
     Q_Q(QLocalSocket);
     // QIODevice signals
-    q->connect(&unixSocket, SIGNAL(aboutToClose()), q, SIGNAL(aboutToClose()));
     q->connect(&unixSocket, SIGNAL(bytesWritten(qint64)),
                q, SIGNAL(bytesWritten(qint64)));
     q->connect(&unixSocket, SIGNAL(readyRead()), q, SIGNAL(readyRead()));

tests/auto/network/socket/qlocalsocket/tst_qlocalsocket.cpp

@@ -468,6 +468,7 @@ void tst_QLocalSocket::connectWithOpen()
     QVERIFY(server.listen("tst_qlocalsocket"));
 
     LocalSocket socket;
+    QSignalSpy spyAboutToClose(&socket, SIGNAL(aboutToClose()));
     socket.setServerName("tst_qlocalsocket");
     QVERIFY(socket.open());
 
@@ -481,6 +482,8 @@ void tst_QLocalSocket::connectWithOpen()
 
     socket.close();
     server.close();
+
+    QCOMPARE(spyAboutToClose.count(), 1);
 }
 
 void tst_QLocalSocket::connectWithOldOpen()