At the same time, allow lxc.mount.entry to specify an absolute target
path relative to /var/lib/lxc/CN/rootfs, even if rootfs is a blockdev.
Otherwise all such entries are ignored for blockdev-backed containers.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>