Upgrading packages from upstream gentoo doesn't work with cros_portage_upgrade if the package uses EAPI=6.

This appears to be because the equery command that it uses under the hood doesn't recognize EAPI=6 as valid.  I'm not sure if there's a short-term hack we can put in to work around this.  The only other option appears to be to upgrade portage itself.

Meanwhile, people will no longer be able to follow the instructions on http://www.chromium.org/chromium-os/gentoo-package-upgrade-process because the tool will not find the new packages.

I have no idea what component this should go under so I'm filing it in infra>client>chromeos for now.