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

@@ -179,11 +179,11 @@
 }
 
 int
 sysevent_subclass_list_walk_init(mdb_walk_state_t *wsp)
 {
-        if (wsp->walk_addr == NULL) {
+        if (wsp->walk_addr == (uintptr_t)NULL) {
                 mdb_warn("sysevent_subclass_list does not support global "
                     "walks");
                 return (WALK_ERR);
         }
 

@@ -194,11 +194,11 @@
 int
 sysevent_subclass_list_walk_step(mdb_walk_state_t *wsp)
 {
         int status;
 
-        if (wsp->walk_addr == NULL)
+        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);

@@ -228,11 +228,11 @@
 int
 sysevent_class_list_walk_init(mdb_walk_state_t *wsp)
 {
         class_walk_data_t *cl_walker;
 
-        if (wsp->walk_addr == NULL) {
+        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);

@@ -257,11 +257,11 @@
         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 (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);