[PATCH] localedata: Avoid concurrently written locales in gen-locale.sh

[Florian Weimer]

* Sam James:

>> +      # (Some versions of mv do not report an error here.)
>> +      mv -Tn $stage ${common_objpfx}localedata/$out 2>/dev/null || true
>
> I'm sorry to ask this, but is mv -T sufficiently portable? It's not
> POSIX but I don't recall if we require any extensions for coreutils
> elsewhere in glibc.

I think I found a portable way to get the expected rename failure.
Well, not really portable because naturally, these details are
unspecified by POSIX.  But I don't think we'll need the special options.

I'll send a new patch.

Thanks,
Florian