CppTools: Use Qt5-style connects

Mostly done by clazy.

Change-Id: I0fbbbe1a2d28b79bcb83093d608bca6e2f927ebb
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/cpptools/cppcodestylepreferences.h

@@ -60,10 +60,9 @@ signals:
 protected:
     virtual QString settingsSuffix() const;
 
-private slots:
+private:
     void slotCurrentValueChanged(const QVariant &);
 
-private:
     CppCodeStyleSettings m_data;
 };