Merge Predef library to release.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@85618 b8fc166d-592f-0410-95f2-cb63ce0dd405
Thread: fix #8417.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@85621 b8fc166d-592f-0410-95f2-cb63ce0dd405
Thread fix #8943.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@85622 b8fc166d-592f-0410-95f2-cb63ce0dd405
Removed SGI copyright as after rewrites it is no longer applicable.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@85626 b8fc166d-592f-0410-95f2-cb63ce0dd405
Removed SGI copyright as after rewrites it is no longer applicable.

git-svn-id: http://svn.boost.org/svn/boost/branches/release@85628 b8fc166d-592f-0410-95f2-cb63ce0dd405