quotearg tests: Fix test failure (regression yesterday).
* tests/testlocale/fr/LC_MESSAGES/gnulib.po: Renamed from
tests/testlocale/fr/LC_MESSAGES/test-quotearg.po.
* tests/testlocale/fr/LC_MESSAGES/gnulib.mo: Renamed from
tests/testlocale/fr/LC_MESSAGES/test-quotearg.mo.
* tests/test-quotearg.c (main): Use bindtextdomain for the domain
"gnulib", not "test-quotearg".
* tests/test-quotearg.sh: Fix typo in comments.
* modules/quotearg-tests (Files): Update.