Core: Use Qt5-style connects

The heavy lifting was done by clazy.

Change-Id: I2dde14919d917816d02117338205f8f861d8af0a
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/plugins/coreplugin/mainwindow.h

@@ -129,7 +129,7 @@ public slots:
 protected:
     virtual void closeEvent(QCloseEvent *event);
 
-private slots:
+private:
     void openFile();
     void aboutToShowRecentFiles();
     void setFocusToEditor();
@@ -143,7 +143,6 @@ private slots:
     void restoreWindowState();
     void newItemDialogFinished();
 
-private:
     void updateContextObject(const QList<IContext *> &context);
     void updateContext();