bug#15260: cannot build in a directory with non-ascii characters

[Eli Zaretskii]

> From: Stefan Monnier <monnier@IRO.UMontreal.CA>
> Cc: handa@gnu.org, 15260@debbugs.gnu.org
> Date: Thu, 31 Oct 2013 09:40:07 -0400
> 
> >> So, it should be removed and replaced by calls to either
> >> make_unibyte_string or make_multibyte_string.
> > I presume you think the same about build_string, then.
> 
> Pretty much, except that I tend to think of build_string as only meant
> for use on string constants, which are all ASCII, normally, so it
> doesn't matter nearly as much.

About 20% of uses of build_string are not guaranteed to act on pure
ASCII strings.