spawn-pipe: close() EINTR handling

[Pádraig Brady]

So I was reading http://austingroupbugs.net/view.php?id=529
which states on Linux that one shouldn't retry close() after EINTR
as the descriptor is already closed in that case
and another thread could reuse the descriptor
which a retried close() would close erroneously.

That suggests that the following code in spawn-pipe is problematic?
Should be remove the retry, and/or do we need to otherwise
handle the SIGSTOP case?

thanks,
Pádraig.

/* EINTR handling for close().
   These functions can return -1/EINTR even though we don't have any
   signal handlers set up, namely when we get interrupted via SIGSTOP.  */

static int
nonintr_close (int fd)
{
  int retval;

  do
    retval = close (fd);
  while (retval < 0 && errno == EINTR);

  return retval;
}
#define close nonintr_close