Fix compiler warning in securesocketclient example

The warning was introduced in a133cea2

 .

Change-Id: Ia8180b6c7d83f57cba79519bf4c0e3bf97966c16
Reviewed-by: Richard J. Moore <rich@kde.org>

examples/network/securesocketclient/sslclient.cpp

@@ -181,7 +181,7 @@ void SslClient::sendData()
     form->sessionInput->clear();
 }
 
-void SslClient::socketError(QAbstractSocket::SocketError error)
+void SslClient::socketError(QAbstractSocket::SocketError)
 {
     QMessageBox::critical(this, tr("Connection error"), socket->errorString());
 }