5218 posix definition of NULL
correct unistd.h and iso/stddef_iso.h
update gate source affected

*** 179,189 ****
  }
  
  int
  sysevent_subclass_list_walk_init(mdb_walk_state_t *wsp)
  {
!         if (wsp->walk_addr == NULL) {
                  mdb_warn("sysevent_subclass_list does not support global "
                      "walks");
                  return (WALK_ERR);
          }
  
--- 179,189 ----
  }
  
  int
  sysevent_subclass_list_walk_init(mdb_walk_state_t *wsp)
  {
!         if (wsp->walk_addr == (uintptr_t)NULL) {
                  mdb_warn("sysevent_subclass_list does not support global "
                      "walks");
                  return (WALK_ERR);
          }
  
*** 194,204 ****
  int
  sysevent_subclass_list_walk_step(mdb_walk_state_t *wsp)
  {
          int status;
  
!         if (wsp->walk_addr == NULL)
                  return (WALK_DONE);
  
          if (mdb_vread(wsp->walk_data, sizeof (subclass_lst_t),
              wsp->walk_addr) == -1) {
                  mdb_warn("failed to read class list at %p", wsp->walk_addr);
--- 194,204 ----
  int
  sysevent_subclass_list_walk_step(mdb_walk_state_t *wsp)
  {
          int status;
  
!         if (wsp->walk_addr == (uintptr_t)NULL)
                  return (WALK_DONE);
  
          if (mdb_vread(wsp->walk_data, sizeof (subclass_lst_t),
              wsp->walk_addr) == -1) {
                  mdb_warn("failed to read class list at %p", wsp->walk_addr);
*** 228,238 ****
  int
  sysevent_class_list_walk_init(mdb_walk_state_t *wsp)
  {
          class_walk_data_t *cl_walker;
  
!         if (wsp->walk_addr == NULL) {
                  mdb_warn("sysevent_class_list does not support global walks");
                  return (WALK_ERR);
          }
  
          cl_walker = mdb_zalloc(sizeof (class_walk_data_t), UM_SLEEP);
--- 228,238 ----
  int
  sysevent_class_list_walk_init(mdb_walk_state_t *wsp)
  {
          class_walk_data_t *cl_walker;
  
!         if (wsp->walk_addr == (uintptr_t)NULL) {
                  mdb_warn("sysevent_class_list does not support global walks");
                  return (WALK_ERR);
          }
  
          cl_walker = mdb_zalloc(sizeof (class_walk_data_t), UM_SLEEP);
*** 257,267 ****
          class_lst_t clist;
  
          cl_walker = (class_walk_data_t *)wsp->walk_data;
  
          /* Skip over empty class table entries */
!         if (wsp->walk_addr != NULL) {
                  if (mdb_vread(&clist, sizeof (class_lst_t),
                      wsp->walk_addr) == -1) {
                          mdb_warn("failed to read class list at %p",
                              wsp->walk_addr);
                          return (WALK_ERR);
--- 257,267 ----
          class_lst_t clist;
  
          cl_walker = (class_walk_data_t *)wsp->walk_data;
  
          /* Skip over empty class table entries */
!         if (wsp->walk_addr != (uintptr_t)NULL) {
                  if (mdb_vread(&clist, sizeof (class_lst_t),
                      wsp->walk_addr) == -1) {
                          mdb_warn("failed to read class list at %p",
                              wsp->walk_addr);
                          return (WALK_ERR);