I took them from https://github.com/boostorg/atomic/commit/6bb71fdd8f7cc346d90fb14beb38b7297fc1ffd9 and https://github.com/boostorg/atomic/commit/e4bde20f2eec0a51be14533871d2123bd2ab9cf3
Just changed the header to match the different location of the files in the stable archive vs the boost::atomic git repo.

Do you want me to add a reference to those commits in boostorg/atomic as a comment?