bug#18556: 24.4.50; update-file-autoloads never ends

[Eli Zaretskii]

> Date: Fri, 26 Sep 2014 09:59:38 -0700
> From: Paul Eggert <eggert@cs.ucla.edu>
> Cc: 18556@debbugs.gnu.org
> 
> I could not reproduce the problem with Emacs trunk bzr 117958 built on 
> Fedora 20 with GCC 4.9.1, in either 32- or 64-bit builds, and in either 
> en_US.UTF-8 or fr_FR.iso885915@euro locales.

And I couldn't reproduce it on MS-Windows with trunk r117955.  It
finishes almost instantly for me.

Vincent, if you attach GDB to the hung Emacs and type "thread apply
all bt" at the GDB prompt, what do you see?