Utils: De-slot and complete Qt5 connects

The only Qt4-style [dis]connects left are in BaseTreeView::setModel.

Change-Id: I53bb715750c65827005cc96939a6714606e60f81
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/libs/utils/textfieldcombobox.h

@@ -46,10 +46,9 @@ public:
 signals:
     void text4Changed(const QString &); // Do not conflict with Qt 3 compat signal.
 
-private slots:
+private:
     void slotCurrentIndexChanged(int);
 
-private:
     inline QString valueAt(int) const;
 };