COMP: Fix unused variable warnings in vtkMRMLTransformStorageNode

This commit fixes the following warnings:

/path/to/Slicer/Libs/MRML/Core/vtkMRMLTransformStorageNode.cxx:396:12: warning: unused variable ‘linear’ [-Wunused-variable]
     double linear[VTKDimension][VTKDimension] = { {1,0,0}, {0,1,0}, {0,0,1}};
            ^
/path/to/Slicer/Libs/MRML/Core/vtkMRMLTransformStorageNode.cxx:397:12: warning: unused variable ‘offset’ [-Wunused-variable]
     double offset[VTKDimension] = {0,0,0};

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23154 3bd1e089-480b-0410-8dfb-8563597acbee