bug#31118: 27.0.50; Can't load/compile websocket in 32bit master

[Eli Zaretskii]

> From: Stefan Monnier <monnier@IRO.UMontreal.CA>
> Date: Wed, 11 Apr 2018 08:19:36 -0400
> Cc: 31118@debbugs.gnu.org
> 
> > $ make externals
> > emacs --batch -l admin/archive-contents.el \
> >     -f archive-add/remove/update-externals
> > No "emacs" subdir: will skip :core packages
> > Cloning branch auctex:

Btw, this part of archive-contents.el:

    (setq archive--use-worktree
          (list
           (ignore-errors
             (zerop (call-process "git" nil nil nil "worktree" "--help"))))))

is sub-optimal: on MS-Windows, Git help commands invoke the system Web
browser to show the HTML version of the docs, so the browser suddenly
pops up when this code runs.

I actually don't understand why --help is the best idea here; is there
something wrong with running "worktree list" instead?  I tested that
with Git v2.3.5, which doesn't support worktrees, and it exited with
non-zero code.