Thread: Add BOOST_THREAD_RV when accessing a BOOST_THREAD_RV_REF to be portable.

[SVN r86439]
Thread: Added a portable copyable/movable nullary_function functor.

[SVN r86440]
Thread: Added a portable copyable/movable thread_pool/executor work.

[SVN r86441]
Thread: adapt thread_pool and executor to the new nullary_function work.

[SVN r86442]
Thread: Adapt barrier to new nullary_function.

[SVN r86443]
Thread: Add a loop to catch more quickly the multiple bugs on boost::future experimental features and see which tester are failing.

[SVN r86444]