This commit fixes the following warning:

Slicer/Libs/vtkAddon/vtkOrientedBSplineTransform.h:64:3: warning: 'GetDisplacementScale' overrides a member function but is not marked 'override' [-Winconsistent-missing-override]
  vtkGetMacro(DisplacementScale,double);
  ^

The function GetDsplacementScale is defined as a public member
function of the base class, and should not be overridden
in the child class.

From: Hans Johnson <hans-johnson@uiowa.edu>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@26363 3bd1e089-480b-0410-8dfb-8563597acbee