QCommandLinkButton: fix visibility of some public functions

The three public functions heightForWidth/minimumSizeHint/sizeHint were
accidentally marked as protected in QCommandLinkButton.
This patch makes sure it get fixed with Qt6.

Fixes: QTBUG-68722
Change-Id: I577e48cbe9274c8506a555dae1ec81044a889d6e
Reviewed-by: Samuel Gaist <samuel.gaist@idiap.ch>
Reviewed-by: Luca Beldi <v.ronin@yahoo.it>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

src/widgets/widgets/qcommandlinkbutton.h

@@ -66,10 +66,16 @@ public:
     QString description() const;
     void setDescription(const QString &description);
 
+    // QTBUG-68722
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
 protected:
+#else
+public:
+#endif
     QSize sizeHint() const override;
     int heightForWidth(int) const override;
     QSize minimumSizeHint() const override;
+protected:
     bool event(QEvent *e) override;
     void paintEvent(QPaintEvent *) override;