Add boost_tuple_iterator_identity to compare iterator correctly.

And add test for boost_tuple_iterator.

test/Jamfile

@@ -60,6 +60,7 @@ project
     [ run sequence/as_set.cpp :  :  :  : ]
     [ run sequence/as_vector.cpp :  :  :  : ]
     [ run sequence/boost_tuple.cpp :  :  :  : ]
+    [ run sequence/boost_tuple_iterator.cpp :  :  :  : ]
     [ run sequence/cons.cpp :  :  :  : ]
     [ run sequence/filter_view.cpp :  :  :  : ]
     [ run sequence/hash.cpp :  :  :  : ]