Squashed 'vendor/src/github.com/kraman/libcontainer/' content from commit d700e5b

git-subtree-dir: vendor/src/github.com/kraman/libcontainer
git-subtree-split: d700e5b21d05486c60f4be3d7bbd3f93065f00c9
Merge commit 'dad3ac8f0022ad0d4576bcc0ea4a70ecb8fcce6f' as 'vendor/src/github.com/kraman/libcontainer'