Update libcontainer to 53cfe0a1eba9145bf5329abbb52
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Update libcontainer Context changes
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Merge pull request #6703 from crosbymichael/update-libcontainer-dep

Update libcontainer to 53cfe0a1eba9145bf5329abb