Changed to use unique_ptr when C++11 is enabled; made other fixes to enable move semantics

git-svn-id: http://svn.boost.org/svn/boost/trunk@86733 b8fc166d-592f-0410-95f2-cb63ce0dd405
Fixed #9401

git-svn-id: http://svn.boost.org/svn/boost/trunk@86734 b8fc166d-592f-0410-95f2-cb63ce0dd405
lockfree: spsc-queue - add read_available and write_available members

git-svn-id: http://svn.boost.org/svn/boost/trunk@86736 b8fc166d-592f-0410-95f2-cb63ce0dd405
lockfree: spsc_queue - call destructors on reset()

git-svn-id: http://svn.boost.org/svn/boost/trunk@86737 b8fc166d-592f-0410-95f2-cb63ce0dd405