Prevent the user from resizing the last wxDataViewCtrl column

This is useless as this column will be automatically expanded to fill
all the available space anyhow.

See #18295.

include/wx/generic/dataview.h

@@ -107,6 +107,8 @@ public:
         return m_flags;
     }
 
+    virtual bool IsResizeable() const wxOVERRIDE;
+
     virtual bool IsSortKey() const wxOVERRIDE
     {
         return m_sort;