COMP: Fix failing implicit conversion from NULL

This patch addressed the following compilation error on certain VS
builds:

c:\Program Files (x86)\Microsoft Visual Studio
10.0\VC\include\utility(163): error C2664:
'itk::SmartPointer<TObjectType>::SmartPointer(const
itk::SmartPointer<TObjectType> &)' : cannot convert parameter 1 from
'int' to 'const itk::SmartPointer<TObjectType> &'

Change-Id: Id66b38e72a6ce2ee2d7887cd9dd8ccc0a7ad6be2
Merge topic 'FixProcessObjectPointerConversion'

d575dac COMP: Fix failing implicit conversion from NULL