use C++11 atomics

Author: kevinushey

src/tbb/include/tbb/machine/macos_common.h

@@ -91,10 +91,10 @@ static inline int64_t __TBB_machine_cmpswp8_OsX(volatile void *ptr, int64_t valu
     fence usages where a more lightweight synchronization means (or none at all)
     could suffice. Thus if you use this header to enable TBB on a new platform,
     consider forking it and relaxing below helpers as appropriate. **/
-#define __TBB_control_consistency_helper() OSMemoryBarrier()
-#define __TBB_acquire_consistency_helper() OSMemoryBarrier()
-#define __TBB_release_consistency_helper() OSMemoryBarrier()
-#define __TBB_full_memory_fence()          OSMemoryBarrier()
+#define __TBB_control_consistency_helper() std::atomic_thread_fence(std::memory_order_seq_cst)
+#define __TBB_acquire_consistency_helper() std::atomic_thread_fence(std::memory_order_seq_cst)
+#define __TBB_release_consistency_helper() std::atomic_thread_fence(std::memory_order_seq_cst)
+#define __TBB_full_memory_fence()          std::atomic_thread_fence(std::memory_order_seq_cst)
 
 static inline int32_t __TBB_machine_cmpswp4(volatile void *ptr, int32_t value, int32_t comparand)
 {