Re: clang fails to compile emacs in Microsoft Windows

[Eli Zaretskii <eliz@gnu.org>]

> From: Biswapriyo Nath <nathbappai@gmail.com>
> Date: Sat, 13 May 2023 01:40:11 +0530
> Cc: Óscar Fuentes <ofv@wanadoo.es>, eliz@gnu.org
> 
> Adding the wait() declaration in nt/inc/sys/wait.h fixes the issue.

That's not the right solution for this issue, though, IMO.  Adding
that declaration is only TRT if you also add some implementation of
'wait' to one of the w32*.c files.

The problem here is that the configure script rejects the sys/wait.h
header we provide for MS-Windows because it deduces it isn't
Posix-compliant enough.  That is the problem to fix: convince the
configure script that our sys/wait.h is fine (which it is, since it
does everything the MS-Windows build needs from it).  The right means
for doing so is the nt/mingw-cfg.site file, where you need to add

  ac_cv_header_sys_wait_h=yes

This will cause this test to succeed unconditionally, which is what we
need.