Another trivial s/linguas_ja/l10n_ja/g rename. (groff-1.22.3 has dropped the linguas_ja flag. Any reason why this hasn't been stabilised yet? It is in the tree since 2014.)
https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=ef59f8cd82ca4807d0ec34508641121ee6e40261