Rename gettext-3 test to intl-setlocale-1.
* gettext-tools/tests/intl-setlocale-1: Renamed from
gettext-tools/tests/gettext-3.
* gettext-tools/tests/intl-setlocale-1-prg.c: Renamed from
gettext-tools/tests/gettext-3-prg.c.
* gettext-tools/tests/intl-setlocale-1-1.po: Renamed from
gettext-tools/tests/gettext-3-1.po.
* gettext-tools/tests/intl-setlocale-1-2.po: Renamed from
gettext-tools/tests/gettext-3-2.po.
* gettext-tools/tests/Makefile.am: Update.
