CppEditor: Use Qt5-style connects

The heavy lifting was done by clazy.

Change-Id: I5ee3678f8293486cccfc634aaab5c75b066ed011
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/cppeditor/cppincludehierarchy.h

@@ -66,14 +66,11 @@ public:
     CppIncludeHierarchyWidget();
     virtual ~CppIncludeHierarchyWidget();
 
-public slots:
     void perform();
 
-private slots:
+private:
     void onItemActivated(const QModelIndex &index);
     void editorsClosed(QList<Core::IEditor *> editors);
-
-private:
     void showNoIncludeHierarchyLabel();
     void showIncludeHierarchy();