build chromium-os for lenovo t430

make sure to use v4.14 kernel, v4.4 doesn't boot:

edit src/overlays/overlay-amd64-generic/profiles/base/make.defaults and change kernel under USE to 4_14
export BOARD=amd64-generic
./setup_board --board=${BOARD} (first build)
cros_workon --board=${BOARD} start chromeos-kernel-4_14
make modifications to the  (add in iwlwifi and disable iwl7000)
src/third_party/kernel/v4.14/chromeos/scripts/./kernelconfig editconfig
src/third_party/kernel/v4.14//make mrproper
./setup_board --board=${BOARD} --force
emerge-amd64-generic chromeos-kernel-4_14
./build_packages --board=${BOARD} chromeos-kernel-4_14
./build_packages --board=${BOARD}
./build_image --board=${BOARD} --noenable_rootfs_verification test