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

*** 242,252 ****
  print_sym(void *pointer)
  {
          int result;
          Dl_info sym_info;
  
!         uintptr_t end = NULL;
  
          Sym *ext_info = NULL;
  
          result = dladdr1(pointer, &sym_info, (void **)&ext_info,
              RTLD_DL_SYMENT);
--- 242,252 ----
  print_sym(void *pointer)
  {
          int result;
          Dl_info sym_info;
  
!         uintptr_t end = (uintptr_t)NULL;
  
          Sym *ext_info = NULL;
  
          result = dladdr1(pointer, &sym_info, (void **)&ext_info,
              RTLD_DL_SYMENT);