Debugger: Make the time stamp recording option work for single items

Should help to drill down to individual expensive dumpers.

Change-Id: I983ba075231784f71dd9d5c3bda375a3ee508bf6
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/debugger/watchhandler.h

@@ -46,6 +46,8 @@ class WatchModelBase : public Utils::TreeModel<WatchItem, WatchItem>
 public:
     WatchModelBase() = default;
 
+    enum { NameColumn, TimeColumn, ValueColumn, TypeColumn };
+
 signals:
     void currentIndexRequested(const QModelIndex &idx);
     void itemIsExpanded(const QModelIndex &idx);