If ocaml-ci has some openbsd runners, would it make sense for oapm-repo-ci to also have some? (ping @shonfeder what do you think?)

Running on 7.6, OpenBSD's pkg_add offers packages gcc and g++ separately. It also includes two versions of g++ so a straight pkg_add g++ returns

Ambiguous: g++ could be g++-11.2.0p15 g++-8.4.0p25

Normally, one would run pkg_add foo-- to avoid this but I can't find an incantation of pkg_add which will install without a prompt. I don't think we should choose a specific version as this will change over time. OpenBSD ships clang++.

@mtelvers so we should have

[ "clang++" ] {os = "openbsd"}

?

And we should probably not have anything for freebsd then?

O asled pffbamd amd @thatportugueseguy doesn't have a way to reproduce (and it seems like ocamlco doesn't do openbsd anymore anyway).

I think we should close this PR and wait for a contribution for someone who can debug it on their machine

re-open if you disagree