Note that this is not the latest (which was 95efd45db073 at time of writing)
but the next commit 6428b4bad0c2 merges "Port ctr to use client package" breaks
the use of `ctr run --runtime-config` (by removing that option).
This contains https://github.com/containerd/containerd/pull/954 which was
causing some services to fail to start.
All previous uses of 15541037b9 are updated to
5749f2e9e6.
Signed-off-by: Ian Campbell <ian.campbell@docker.com>
