Be slightly defensive
Move files around
Squashed 'ck/' content from commit 7fc90eb

git-subtree-dir: ck
git-subtree-split: 7fc90ebf25000fbf37056731c54668f61b4c2bb4
Merge commit 'dce2bdd104331145b0e5a4192024620fab0c4391' as 'ck'
[Build] Make and link concurrency kit

Concurrency kit provides a nice range of sensible looking code for
things like the hazard pointers and CAS primitives.