Linux standalone: Add back the LOCPATH=/dev/null hack to avoid the system locale...

Linux standalone: Add back the LOCPATH=/dev/null hack to avoid the system locale-archive being read.

Version mismatches between the system locale-archive and the glibc in the
bundle have been observed to cause git crashes.

Unfortunately, this causes locales to not be used in the linux standalone
bundle, as was the case until version 6.20160419.

glibc hardcodes the path to /usr/lib/locale/locale-archive and does not
let an environment variable cause a different locale-archive file to be used.

The only other option to include locales in the bundle would be to include
exploded locale definition directories in the bundle for a number of
locales, generated by localedef. But these take at least 300 kb per locale,
and there are a great many locales; it would be hundreds of megabytes to
include them all.

(Hmm, we could include localdef in the bundle, and check LANG in runshell
and compile the locale directories on the fly. This would need
/usr/share/i18n/ and /usr/lib/locale-archive to be included in the bundle.
It's.. doable.)

I know this is going to once again cause users of the bundle to complain
that eg, ls doesn't show their unicode filenames right. Better than strange
crashes though.