QScreen manual test: show names of enum values

It's more user-friendly to show
    primaryOrientation LandscapeOrientation
instead of
    primaryOrientation 2

Change-Id: Ic1659b9253cd492bef347d6840cf3cf6e6d2c94f
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

tests/manual/qscreen/propertyfield.cpp

@@ -44,6 +44,9 @@ PropertyField::PropertyField(QObject* subject, const QMetaProperty& prop, QWidge
 
 QString PropertyField::valueToString(QVariant val)
 {
+    if (m_prop.isEnumType())
+        return QString::fromUtf8(m_prop.enumerator().key(val.toInt()));
+
     QString text;
     switch (val.type()) {
     case QVariant::Double: