move Freeze() and Thaw() to wxWindowBase to ensure that they behave consistently (i.e. recursively, as described in the docs) in all ports; removed different duplications of freeze count from derived classes

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@51018 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/generic/listctrl.h

@@ -174,9 +174,6 @@ public:
     virtual void Refresh(bool eraseBackground = true,
                          const wxRect *rect = NULL);
 
-    virtual void Freeze();
-    virtual void Thaw();
-
     virtual bool SetBackgroundColour( const wxColour &colour );
     virtual bool SetForegroundColour( const wxColour &colour );
     virtual wxColour GetBackgroundColour() const;
@@ -218,6 +215,9 @@ protected:
 
     virtual wxSize DoGetBestSize() const;
 
+    virtual void DoFreeze();
+    virtual void DoThaw();
+
     // return the text for the given column of the given item
     virtual wxString OnGetItemText(long item, long column) const;