Remove reference to Symbian in QtNetwork.

Change-Id: Iae377505e36ae1239be7ce52c773dc2a4f4a9767
Reviewed-by: Jonas Gastal <jgastal@profusion.mobi>
Reviewed-by: Peter Hartmann <peter.hartmann@nokia.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

src/network/bearer/qnetworksession.cpp

@@ -575,8 +575,6 @@ void QNetworkSession::migrate()
 */
 void QNetworkSession::ignore()
 {
-    // Needed on mobile platforms (was needed for Symbian/S60): the roaming must be explicitly
-    // ignore()'d or migrate()'d
     if (d)
         d->ignore();
 }

src/network/socket/qudpsocket.cpp

@@ -318,9 +318,6 @@ qint64 QUdpSocket::pendingDatagramSize() const
     fragmented by the IP layer before arriving at their final
     destination.
 
-    \warning In S60 5.0 and earlier versions, the writeDatagram return
-    value is not reliable for large datagrams.
-
     \warning Calling this function on a connected UDP socket may
     result in an error and no packet being sent. If you are using a
     connected socket, use write() to send datagrams.