We need clang-format available in order to check for formatting errors later.
Add it to the amd64 container only (this requires some shenigans to avoid
multi-arch conflicts).
Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Reviewed-by: Eric Engestrom <eric@igalia.com>
Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20553>