test-gendoc: require gettext
If the gettext utilities aren't installed, there is no way to make the
translations. This causes the gettext client to fall back to the untranslated
message, which triggers "** NOTHING TRANSLATED **" errors and a test failure.
To run the tests, do:
cd tests/
python run-tests.py
See http://mercurial.selenic.com/wiki/WritingTests for
more information on writing tests.