Boost.Atomic and Boost.Lockfree merged from trunk.
atomic: merge fixes from trunk
Removed unnecessary fences, added pause operations to tight spin loops to optimize power consumption and performance on HT-enabled systems.
Attempt to fix compilation on Windows CE. Restored full fence in the platform_fence_after_load function on architectures other than x86 and x86_64. The fence is not required only on those architectures.
Added missing atomic typedefs.
Fixed compilation on PGI.
Attempt to fix compilation in Windows CE.
atomic: merge documentation fix from trunk
Atomic: merge from trunk.
atomic: merge fixes from trunk