add boost on mac

macx64/include/boost/logic/tribool_fwd.hpp

@@ -0,0 +1,15 @@
+// Three-state boolean logic library
+
+// Copyright Douglas Gregor 2002-2004. Use, modification and
+// distribution is subject to the Boost Software License, Version
+// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+
+// For more information, see http://www.boost.org
+#ifndef BOOST_LOGIC_TRIBOOL_FWD_HPP
+#define BOOST_LOGIC_TRIBOOL_FWD_HPP
+
+namespace boost { namespace logic { class tribool; } }
+
+#endif // BOOST_LOGIC_TRIBOOL_FWD_HPP