Rename the default organisation from "Trolltech" to "Qt" on Mac

This doesn't seem to be documented -- or if it was, the documentation
has been changed.

Task-number: QTBUG-23269
Change-Id: Ie7aa51aeb251bfaa3d0018fbac4adc9517c97fa0
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

src/corelib/io/qsettings_mac.cpp

@@ -604,7 +604,7 @@ QSettingsPrivate *QSettingsPrivate::create(QSettings::Format format,
                                            const QString &application)
 {
 #ifndef QT_BOOTSTRAPPED
-    if (organization == QLatin1String("Trolltech"))
+    if (organization == QLatin1String("Qt"))
     {
         QString organizationDomain = QCoreApplication::organizationDomain();
         QString applicationName = QCoreApplication::applicationName();