Seems I can't "unforget" erroneously forgotten files, so will have to forget them and then re-add them
#ifndef BOOST_DETAIL_ATOMIC_COUNT_HPP_INCLUDED
#define BOOST_DETAIL_ATOMIC_COUNT_HPP_INCLUDED
// MS compatible compilers support #pragma once
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
//
// boost/detail/atomic_count.hpp - thread/SMP safe reference counter
//
// Copyright (c) 2001, 2002 Peter Dimov and Multi Media Ltd.
//
// Distributed under the Boost Software License, Version 1.0.
// See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt
#include <boost/smart_ptr/detail/atomic_count.hpp>
#endif // #ifndef BOOST_DETAIL_ATOMIC_COUNT_HPP_INCLUDED