private auxilary member functions

Author: pcarruscag

SU2_CFD/include/output/filewriter/CCGNSFileWriter.hpp

@@ -79,6 +79,8 @@ class CCGNSFileWriter final : public CFileWriter {
    * \brief Write sorted data to file in CGNS file format.
    */
   void Write_Data() override;
+  
+ private:
 #ifdef HAVE_CGNS
   /*!
    * \brief Initialize CGNS mesh file.