Remove superfluous call in QProcessPrivate::_q_startupNotification

There is no need to disable startupSocketNotifier because the call to
QProcessPrivate::processStarted() will do that.

Change-Id: I20b816533d9a5c4b9bf57135d26166c961a07d07
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>

src/corelib/io/qprocess.cpp

@@ -1208,8 +1208,6 @@ bool QProcessPrivate::_q_startupNotification()
     qDebug("QProcessPrivate::startupNotification()");
 #endif
 
-    if (startupSocketNotifier)
-        startupSocketNotifier->setEnabled(false);
     QString errorMessage;
     if (processStarted(&errorMessage)) {
         q->setProcessState(QProcess::Running);