Skip /dev setup in container when it is bind mounted in #16639 https://github.com/docker/docker/pull/16639
This patch fixed some breakages where a user wanted to share /dev from the host into the container. Super Privileged Containers (SPC) often need this feature. For example. docker run -v /dev:/dev ... The classic example of this would be a SPC needing to create new devices to be used on the host. Running libvirt inside of a container launching VM's needs this feature.
