Restore virtual keyword for Kokkos package

  virtual void force_clear(int, size_t) {}

  void grow(int);

  virtual void grow(int);

  virtual void grow_pointers() {}

  void copy(int, int, int);

  virtual void copy(int, int, int);

  virtual void copy_bonus(int, int, int) {}

  virtual void clear_bonus() {}

  int pack_comm(int, int *, double *, int, int *);

  int pack_comm_vel(int, int *, double *, int, int *);

  void unpack_comm(int, int, double *);

  void unpack_comm_vel(int, int, double *);

  virtual int pack_comm(int, int *, double *, int, int *);

  virtual int pack_comm_vel(int, int *, double *, int, int *);

  virtual void unpack_comm(int, int, double *);

  virtual void unpack_comm_vel(int, int, double *);

  virtual int pack_comm_bonus(int, int *, double *) {}

  virtual void unpack_comm_bonus(int, int, double *) {}

  int pack_reverse(int, int, double *);

  void unpack_reverse(int, int *, double *);

  virtual int pack_reverse(int, int, double *);

  virtual void unpack_reverse(int, int *, double *);

  int pack_border(int, int *, double *, int, int *);

  int pack_border_vel(int, int *, double *, int, int *);

  void unpack_border(int, int, double *);

  void unpack_border_vel(int, int, double *);

  virtual int pack_border(int, int *, double *, int, int *);

  virtual int pack_border_vel(int, int *, double *, int, int *);

  virtual void unpack_border(int, int, double *);

  virtual void unpack_border_vel(int, int, double *);

  virtual int pack_border_bonus(int, int *, double *) {}

  virtual int unpack_border_bonus(int, int, double *) {}

  int pack_exchange(int, double *);

  int unpack_exchange(double *);

  virtual int pack_exchange(int, double *);

  virtual int unpack_exchange(double *);

  virtual int pack_exchange_bonus(int, double *) {}

  virtual int unpack_exchange_bonus(int, double *) {}

  int size_restart();

  int pack_restart(int, double *);

  int unpack_restart(double *);

  virtual int size_restart();

  virtual int pack_restart(int, double *);

  virtual int unpack_restart(double *);

  virtual void pack_restart_pre(int) {}

  virtual void pack_restart_post(int) {}

  virtual int pack_restart_bonus(int, double *) {}

  virtual int unpack_restart_bonus(int, double *) {}

  void create_atom(int, double *);

  virtual void create_atom(int, double *);

  virtual void create_atom_post(int) {}

  void data_atom(double *, imageint, char **);

  virtual void data_atom(double *, imageint, char **);

  virtual void data_atom_post(int) {}

  virtual void data_atom_bonus(int, char **) {}

  virtual void data_body(int, int, int, int *, double *) {}

  void pack_data(double **);

  void write_data(FILE *, int, double **);

  virtual void pack_data(double **);

  virtual void write_data(FILE *, int, double **);

  virtual void pack_data_pre(int) {}

  virtual void pack_data_post(int) {}

  void data_vel(int, char **);

  void pack_vel(double **);

  void write_vel(FILE *, int, double **);

  virtual void data_vel(int, char **);

  virtual void pack_vel(double **);

  virtual void write_vel(FILE *, int, double **);

  int pack_bond(tagint **);

  void write_bond(FILE *, int, tagint **, int);

  int pack_angle(tagint **);

  void write_angle(FILE *, int, tagint **, int);

  int pack_dihedral(tagint **);

  void write_dihedral(FILE *, int, tagint **, int);

  int pack_improper(tagint **);

  void write_improper(FILE *, int, tagint **, int);

  virtual int pack_bond(tagint **);

  virtual void write_bond(FILE *, int, tagint **, int);

  virtual int pack_angle(tagint **);

  virtual void write_angle(FILE *, int, tagint **, int);

  virtual int pack_dihedral(tagint **);

  virtual void write_dihedral(FILE *, int, tagint **, int);

  virtual int pack_improper(tagint **);

  virtual void write_improper(FILE *, int, tagint **, int);

  virtual int property_atom(char *) {return -1;}

  virtual void pack_property_atom(int, double *, int, int) {}

  bigint memory_usage();

  virtual bigint memory_usage();

  virtual bigint memory_usage_bonus() {}

 protected: