typo fix: create $rootfs/dev/pts

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
don't run lxc-user-nic for empty netns

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
coverity : fix memleak on error path

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>