http://search.cpan.org/~audreyt/Unicode-EastAsianWidth-1.30/lib/Unicode/EastAsianWidth.pm I'll add it myself if noone else beats me to it. Reporting for now so I don't forget. After added, app-text/texi2html could gain a revision bump with USE=cjk and --with-external-Unicode-EastAsianWidth
In portage.