Re: master 2c79a8f 2/2: Use posix_spawn if possible.

[Eli Zaretskii]

> From: Philipp Stephani <p.stephani2@gmail.com>
> Date: Tue, 29 Dec 2020 22:36:40 +0100
> Cc: Emacs developers <emacs-devel@gnu.org>
> 
> >     CC       getdtablesize.o
> >   getdtablesize.c:58:1: warning: no previous prototype for 'getdtablesize' 
> > [-Wmissing-prototypes]
> >      58 | getdtablesize (void)
> >         | ^~~~~~~~~~~~~
> 
> Ah, I guess this is because the MinGW build excludes Gnulib's unistd.h
> etc. So for now it looks like we do have to exclude the spawn modules
> from the Windows build (unless we can include the POSIX headers from
> Gnulib).

The Gnulib unistd.h caused trouble in the MinGW build, so we disabled
it long ago.  On the trunk, we don't compile getdtablesize.c, either,
and I don't see why we would need to.

(It's not that we always exclude headers from Gnulib on Windows, we
only do that with headers that cause trouble.)