COMP: Explicitly add override to GetNameOfClass method

This patch addressed the following warning:

/Users/builder/external/ITK/Modules/Core/Common/include/itkObject.h:77:3:
warning: 'GetNameOfClass' overrides a member function but is not
marked 'override' [-Winconsistent-missing-override]
  itkTypeMacro(Object, LightObject);
  ^
/Users/builder/external/ITK/Modules/Core/Common/include/itkMacro.h:233:23:
note: expanded from macro 'itkTypeMacro'
  virtual const char *GetNameOfClass() const \

Change-Id: I53a0a07ec96701af6b49f59754956c802c1dbfe4
Merge topic 'AddOverrideToGetNameOfClass'

2cc5ae27 COMP: Explicitly add override to GetNameOfClass method