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

@@ -232,11 +232,11 @@
         }
         commd_err.size = strlen(msg_buf);
         commd_err.md_message = (uint64_t)(uintptr_t)&msg_buf[0];
 
         (void) metaioctl(MD_MN_COMMD_ERR, &commd_err, &mne, "rpc.mdcommd");
-        (void) uadmin(A_DUMP, AD_BOOT, NULL);
+        (void) uadmin(A_DUMP, AD_BOOT, (uintptr_t)NULL);
 }
 
 static void
 flush_fcout()
 {