coreos/stage1_hooks: Add a hook for pulling a newer version of baselayout

Pull in a new version of baselayout to have a proper setup of lib
directories in stage1. The proper setup means that the `lib` entry is
now a directory instead of a symlink to `lib64`.

Honestly, when rewording this commit, I realized that this hook is not
really needed, as the updated baselayout ebuild just drops code that
became dead after the profile update that the other hook does. But I
decided to keep it as is, because the CI build with this hook has
passed, and this hook will be needed anyway by the weekly updates.

sdk_container/src/third_party/coreos-overlay/coreos/stage1_hooks/0000-bump-baselayout-coreos-overlay.sh

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+set -euo pipefail
+
+stage1_repo="${1}"
+new_repo="${2}"
+
+good_version="3.6.8-r9"
+stage1_version=''
+
+for f in "${stage1_repo}/sys-apps/baselayout/baselayout-"*'.ebuild'; do
+    f="${f##*/}"
+    if [[ "${f}" = *9999* ]]; then continue; fi
+    f="${f%.ebuild}"
+    f="${f#baselayout-}"
+    stage1_version="${f}"
+done
+
+if [[ -z "${stage1_version}" ]]; then exit 1; fi
+
+older_version=$(printf '%s\n' "${stage1_version}" "${good_version}" | sort -V | head -n 1)
+
+if [[ "${older_version}" = "${good_version}" ]]; then
+    # Stage1 version is equal or newer than the good version, nothing
+    # to do.
+    exit 0
+fi
+
+rm -rf "${stage1_repo}/sys-apps/baselayout"
+cp -a "${new_repo}/sys-apps/baselayout" "${stage1_repo}/sys-apps/baselayout"