include guards for vtk

Modules/LemmaCore/src/RectilinearGridVTKImporter.cpp

  * @copyright Copyright (c) 2018, Lemma Software, LLC
  */
 
+#if LEMMAUSEVTK
+
 #include "RectilinearGridVTKImporter.h"
 
 namespace Lemma {
 /* vim: set tabstop=4 expandtab: */
 /* vim: set filetype=cpp: */
 
+#endif     // -----  not LEMMAUSEVTK  -----