[boost] serializing a hash_map (tweaks for gcc-3.3.4/libstdc++-v3)

Had a couple problems serializing a hash map on gcc-3.3.4/gnu libstdc++-v3. Sorry if this is a repeat, I've googled around a bit and found nothing. Here are the tweaks necessary: 1. BOOST_HAS_HASH is not defined for this stdlib, needs to be turned on. 2. The <hash_map> header itself is not accessible as <hash_map>, it's <ext/hash_map>, and 3. The BOOST_STD_EXTENSION_NAMESPACE in this case is "__gnu_cxx". I have a patched stdlibcpp3.hpp and serialization/hash_map.hpp if somebody wants 'em... Cheers, -t