hard_locale in a single-threaded app

[Paul Eggert]

I tried to update GNU diffutils to the latest Gnulib, and found that 
this dragged in a bunch of stuff about multithreading that diffutils 
doesn't need. The first function I found was hard_locale. What's the 
recommended way to use hard_locale in a single-threaded app, without 
pulling in the thread library part of Gnulib?

Also, a couple of the multithread-based Gnulib tests failed in the 
updated diffutils, but only there - they don't fail standalone. I assume 
this is because diffutils is excluding some modules (based on what it 
needed to do with old Gnulib to avoid the threading stuff), so I doubt 
whether this rabbit hole is worth going down. The main problem is to use 
modules like hard_locale without worrying about threading.