bug#47596: File descriptor error when exiting emacs on android 11

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: eliz@gnu.org,  47596@debbugs.gnu.org
> Date: Wed, 12 May 2021 15:52:52 +0200
> 
> Henrik Grimler <henrik@grimler.se> writes:
> 
> > Could this work or do we need to have both buferr and stderr?
> 
> Makes sense to me, but I seem to vaguely recall there being a lot of
> discussion about the buffered stderr when it was introduced...  but none
> of the details.  Eli?

We need them both, yes.  The second one was introduced for a reason,
so removing it would give us back the problems it solved.

setlinebuf is not portable enough, and line buffering isn't supported
on MS-Windows anyway.  Maybe we could make some archlinux specific
change, although that's ugly.

And I'm worried that we don't actually understand the nature of the
problem well enough: our code doesn't close both FILE streams, it
closes at most only one.  So this sounds to me like a false positive
of the sanitizer, not a real problem with our code...