remove redundant declaration
otherwise we can end up with errors like:
ERROR: In e:\vtk\source\rendering\opengl2\vtkshaderprogram.cxx, line 480
vtkShaderProgram (0000000006567710): ERROR: 0:42: 'vertexVCVSOutput' : redeclaring non-array as array
or
ERROR: In e:\vtk\source\rendering\opengl2\vtkshaderprogram.cxx, line 480
vtkShaderProgram (000001F2BC8CEA30): Geometry shader failed to compile with the following errors:
ERROR: 0:32: error(#191) Redeclaration of array with size: vertexVCVSOutput
Backport: release
Edited by Mathieu Westphal (Kitware)