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

*** 951,961 ****
  
                                  len = strlen(func_strs[MODE]);
                                  if ((strncmp(str, func_strs[MODE], len) == 0) &&
                                      (*(str+(len)) == '=')) {
                                          for (str = (str+(++len)), i = 0;
!                                             *str != NULL; i++, str++) {
                                                  buf[i] = *str;
                                          }
                                  }
                                  buf[i] = '\0';
                                  DBG(2, ("buf_mode= %s\n", buf));
--- 951,961 ----
  
                                  len = strlen(func_strs[MODE]);
                                  if ((strncmp(str, func_strs[MODE], len) == 0) &&
                                      (*(str+(len)) == '=')) {
                                          for (str = (str+(++len)), i = 0;
!                                             *str != '\0'; i++, str++) {
                                                  buf[i] = *str;
                                          }
                                  }
                                  buf[i] = '\0';
                                  DBG(2, ("buf_mode= %s\n", buf));