If the user specifies a mountpath from the host, we should not be
attempting to chown files outside the daemon's metadata directory
(represented by `daemon.repository` at init time).
This forces users who want to use user namespaces to handle the
ownership needs of any external files mounted as network files
(/etc/resolv.conf, /etc/hosts, /etc/hostname) separately from the
daemon. In all other volume/bind mount situations we have taken this
same line--we don't chown host file content.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>