* Use `--userns` to become `builduser` right away instead of using `sudo`
to become `builduser`
* Add `builduser` to `sudoers` so it can become root to synchronize
packages
* Ensure this way that files created within the container have the
user/group of the user starting the container so build artifacts have the
right ownership
This is useful to invoke `updpkgsums` or `repo-add` within the container as
well. These tools also seem to need the additional logic to use a dedicated
build user so it makes sense to make this part of `makecontainerpkg`.
* Add my GPG key to the pacman keyring (not nice to hard-code it in the
Dockerfile but good enough for now)
* Install ccache into the base image to support makepkg's ccache option
* Split syncing packages and execution of `makepkg` so syncing can be
avoided when only building source package
* Don't quote `CRE`, it is unlikely spaces are needed here and using
chained commands (e.g. `sudo …`) might be useful
* Add documentation
* Allow building Arch Linux packages within a "standard" container similar
to how `makechrootpkg` allows building packages within a systemd-nspawn
container
* Add a Dockerfile to create an Arch Linux image suitable for package
builds via `makepkg`
Martchus