Update libcontainer to cf45d141db69ce11dcccac178e5

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Merge pull request #7109 from crosbymichael/update-libcontainer-july4

Update libcontainer to cf45d141db69ce11dcccac178e5