Move CheckAtomic cmake module out of the shared cmake dir
Move CheckAtomic cmake module out of the shared cmake dir

Summary: Remove the shared CheckAtomic cmake module out of the shared dir and back to the projects that need it.

Reviewed By: lukaspiatkowski

Differential Revision: D19553656

fbshipit-source-id: 5e89b5b9448ef6d6c57ef904a652e9f9a1d5dbb3

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly