Merge commit 'ce929fe84f9c453263af379f3b255ff8eca01d48'

Import CK as of commit 2265c7846f4ce667f5216456afe2779b23c3e5f7.

Import Concurrency Kit in the kernel.
CK is a toolkit providing different lockfree algorithms/data structures.
More information can be found here : www.concurrencykit.org