Fix unintended source compatiblity break in QSslSocket

QSslSocket overrides one version of QAbstractSocket::connectToHost.
Since these functions were made virtual, this now hides the other
overloads.
Added a using statement to make the other overloads visible.

Change-Id: Ia48fdc9bd67936c75c25bb24dabd26a723bb7a05
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/network/ssl/qsslsocket.h

@@ -90,6 +90,7 @@ public:
     bool setSocketDescriptor(qintptr socketDescriptor, SocketState state = ConnectedState,
                              OpenMode openMode = ReadWrite);
 
+    using QAbstractSocket::connectToHost;
     void connectToHost(const QString &hostName, quint16 port, OpenMode openMode = ReadWrite, NetworkLayerProtocol protocol = AnyIPProtocol);
     void disconnectFromHost();