fix(dev-libs/libdivsufsort): RESTRICT="mirror"

the gentoo mirrors don't have this package, download from Google code
for now.
fix(coreos-base/libchromeos): bump to 180609
bump(coreos-base/libchrome): bump to 180609

also remove the wno-c++11 flag which is breaking with our compiler
fix(coreos-base/update_engine): fix -9999 version

- fixup the dependencies to point at coreos-base
- point at 180609 version of libchrome
feat(coreos-base/coreos): re-add update_engine

It is compiling now re-enable update_engine for the VM builds.
chore(eclass): remove unneeded stuff

I imported a bunch of stuff needlessly when I first started working,
remove it.
chore(eclass): bump to latest code from chromeos
chore(sys-devel/binutils): re-import from chromeos

we need/want -gold. re-import from chromeos and remove from
portage-stable
fix(dev-libs/dbus-c++): patch to fix pthread

In the future we should provide our own tarball based on the git source
code but this is fine for now.
fix(coreos/config): use both osuosl and chromeos mirrors

we need chromeos mirrors for stable packages and osuosl for new ones. In
the future we will mirror our own stable packages.
bump(coreos-base/metrics): bump to use latest libchrome

get this building against the new libchrome
bump(coreos-base/update_engine): get new libchrome
fix(coreos-base/update_engine): use git

use git for update_engine while we are hacking on it
fix(coreos-base/coreos): add crosh