Changes included: 2 changes.

Change 475875fb741765cd32d021b9ed498fc23f41ea75 by andrew hanushevsky <[log in to unmask]> (1 file): Update notes on atomics extensions and correct use.

Change 87db43fc0bac9ece2cb37660587c5d6e901842c4 by andrew hanushevsky <[log in to unmask]> (2 files): Add AtomicZAP() to avoid gcc warnings about "no effect" statements on platforms
that do not have builtin atomic operations.