[boost] Patch for building Boost with GCC 4.4.0

GCC changed the way #elif's are handled (is now more std-compliant apparently) but this broke all the #elif BOOST_PP_ITERATION_DEPTH() == N lines. They need to be replaced with #elif defined(BOOST_PP_ITERATION_DEPTH) #if BOOST_PP_ITERATION_DEPTH == N ... #endif Attached is a patch that does so (against trunk). Cheers, Chris