[boost] Moving workaround headers to [config] Was: throw or boost::throw_exception?

John Maddock wrote:

I'm starting to wonder if all the "workaround" headers should be moved into Config (provided they don't depend on anything else). This would be one candidate I guess?

Possible others would be

boost/cerrno.gpp boost/cstdlib.hpp boost/cstdint.hpp

boost/iterator.hpp is another candidate. It's currently in Iterator but is a workaround header that does not depend on anything. There is also boost/detail/iterator.hpp, in Detail. It's also a workaround header. It conditionally includes type traits and MPL headers though. But I think that it only does that on MSVC 6, which we no longer support (the #ifdef is on BOOST_MSVC_STD_ITERATOR). boost/iterator/iterator_traits.hpp, in turn, only depends on boost/detail/iterator.hpp.