Warnings with -Wundef

[driscoll@…]

Compiling with GCC 4.3.2 on Linux with -Wundef -Werror:

In file included from boost_1_49_0_beta1/boost/intrusive/detail/memory_util.hpp:112,
                 from boost_1_49_0_beta1/boost/intrusive/pointer_traits.hpp:26,
                 from boost_1_49_0_beta1/boost/intrusive/detail/utilities.hpp:17,
                 from boost_1_49_0_beta1/boost/intrusive/list_hook.hpp:19,
                 from boost_1_49_0_beta1/boost/intrusive/list.hpp:20,
                 from boost_1_49_0_beta1/boost/heap/detail/heap_node.hpp:14,
                 from boost_1_49_0_beta1/boost/heap/binomial_heap.hpp:18,
                 ...
boost_1_49_0_beta1/boost/intrusive/detail/has_member_function_callable_with.hpp:13:6: error: "BOOST_PP_IS_ITERATING" is not defined

[Ion Gaztañaga]

Fixed in Boost 1.50