tests: splitting test-gendoc.t into per file tests
Localizers can now run test-gendoc-$LOCALE.t instead of
test-gendoc.t.
After this change, test-gendoc.t only checks whether there is *some*
localization for the expected set of languages and no others.
Whenever a locale i18n/$LOCALE.po is added, someone needs
to add test-gendoc-$LOCALE.t
#require docutils gettext
$ $TESTDIR/check-gendoc da
checking for parse errors