Clean up the last of QT6_(NOT_)?VIRTUAL

This follows up on commit d273076b4474bb473d90e996960c4c773745761a
which left a comment asking for the clean-up this finishes.

Task-number: QTBUG-85700
Change-Id: I1c6896a42a09b873302ad7ec8273879f2a4a4ce6
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

src/corelib/global/qglobal.h

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2019 The Qt Company Ltd.
+** Copyright (C) 2020 The Qt Company Ltd.
 ** Copyright (C) 2019 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
@@ -77,10 +77,6 @@
 #define QT_CONFIG(feature) (1/QT_FEATURE_##feature == 1)
 #define QT_REQUIRE_CONFIG(feature) Q_STATIC_ASSERT_X(QT_FEATURE_##feature == 1, "Required feature " #feature " for file " __FILE__ " not available.")
 
-// ### Clean those up, once all code is adjusted
-#define QT6_VIRTUAL virtual
-#define QT6_NOT_VIRTUAL
-
 /* These two macros makes it possible to turn the builtin line expander into a
  * string literal. */
 #define QT_STRINGIFY2(x) #x

src/widgets/graphicsview/qgraphicsscene.h

@@ -268,7 +268,7 @@ protected:
                            QWidget *widget = nullptr);
 
 protected Q_SLOTS:
-    QT6_VIRTUAL bool focusNextPrevChild(bool next);
+    virtual bool focusNextPrevChild(bool next);
 
 Q_SIGNALS:
     void changed(const QList<QRectF> &region);

src/widgets/kernel/qlayout.h

@@ -123,7 +123,7 @@ public:
     bool isEmpty() const override;
     QSizePolicy::ControlTypes controlTypes() const override;
 
-    QT6_VIRTUAL QLayoutItem *replaceWidget(QWidget *from, QWidget *to,
+    virtual QLayoutItem *replaceWidget(QWidget *from, QWidget *to,
                                        Qt::FindChildOptions options = Qt::FindChildrenRecursively);
 
     int totalHeightForWidth(int w) const;

src/xml/sax/qxml.h

@@ -149,7 +149,7 @@ public:
     QXmlAttributes &operator=(const QXmlAttributes &) = default;
     QXmlAttributes &operator=(QXmlAttributes &&) noexcept = default;
 
-    QT6_NOT_VIRTUAL ~QXmlAttributes();
+    ~QXmlAttributes();
 
     void swap(QXmlAttributes &other) noexcept
     {