Adding a line

    .\" -*- mode: nroff; coding: utf-8 -*-

apparently makes groff/nroff to recognize file as UTF8 and makes it
behave accordingly (so even PS files are generated correctly).

I have added this to all manapges which seem to matter (although not
sure with strlcpy.3 and other standard library functions ... why there
are special manpages in the repo anyway?).