localedata: Locale and test name are the same.

The localedata collation test data is encoded in a particular
character set. We rename the test data to match the full locale
name with encoding, and adjust the Makefile and sort-test.sh
script. This allows us to have a future C.UTF-8 test that is
disambiguated from the built-in C locale.

Signed-off-by: Carlos O'Donell <carlos@redhat.com>