Done.  I wrote 64-bit.eclass and demonstrated its use in
ncurses-5.3-r4.ebuild:

    inherit flag-o-matic 64-bit

    src_compile() {
        64-bit && append-flags -fPIC
        ...
    }

Aron

P.S. Jon, please forward to gentoo-amd64.  I can't post there because
I'm not subscribed.

-- 
Aron Griffis
Gentoo Linux Developer (alpha / ia64 / ruby / vim)
Key fingerprint = E3B6 8734 C2D6 B5E5 AE76  FB3A 26B1 C5E3 2010 4EB0