>
> Does _exit in glibc provide any hooks that we could use?  Emacs cannot 
> be the first application that doesn't want misbehaving libraries to 
> forcibly exit it.
>

It's possible (albeit tricky) to escape an _exit() call by using 
LD_PRELOAD, see attached example.  Whether this is usable for Emacs, I 
don't know.