Removed unused method

Fixed -Wunused-member-function warning, the only
such warning in the codebase.

Change-Id: I8c2fe36cd1dc07475711cb454d2327b6b7a9c50b

IO/Core/vtkTextCodec.cxx

@@ -61,7 +61,6 @@ namespace
     ~vtkUnicodeStringOutputIterator();
 
   private:
-    vtkUnicodeStringOutputIterator(); // Not implemented
     vtkUnicodeStringOutputIterator(const vtkUnicodeStringOutputIterator&); // Not implemented
     const vtkUnicodeStringOutputIterator& operator=(const vtkUnicodeStringOutputIterator&); // Not Implemented