Fix missing override warning

Change-Id: Ib0616b203f3cf2934b7a0fd18b95111423001bab
Reviewed-by: Jan Grulich <jgrulich@redhat.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/plugins/platformthemes/flatpak/qflatpaktheme.h

@@ -72,7 +72,7 @@ public:
 
     QPixmap standardPixmap(StandardPixmap sp, const QSizeF &size) const override;
     QIcon fileIcon(const QFileInfo &fileInfo,
-                   QPlatformTheme::IconOptions iconOptions = 0) const;
+                   QPlatformTheme::IconOptions iconOptions = 0) const override;
 
     QIconEngine *createIconEngine(const QString &iconName) const override;