COMP: Must specify order as "noexcept override"

The two keywords can be used together but the order must be "noexcept
override".  The grammar production rule specifies exceptions first
(throw(), noexcept) and virtual things later (override, final).

Addressed the following issue:
itkObject.h:105:16: error: exception specification of overriding
function is more lax than base version
  virtual void UnRegister() const ITK_OVERRIDE ITK_NOEXCEPT;

Change-Id: I83e715dc67968a564965d7ec9ef32f91f6e40d01
Co-authored-by: Brad King <brad.king@kitware.com>
Merge topic 'FixNoexceptWithAssert'

ec024168 COMP: Must specify order as "noexcept override"