Commented out export of missing CRML source file to avoid build error.
There are no known side effects of this file being missing, so this seems a reasonable way to avoid the build error.
//-----------------------------------------------------------------------------
// boost blank_fwd.hpp header file
// See http://www.boost.org for updates, documentation, and revision history.
//-----------------------------------------------------------------------------
//
// Copyright (c) 2003
// Eric Friedman
//
// 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)
#ifndef BOOST_BLANK_FWD_HPP
#define BOOST_BLANK_FWD_HPP
namespace boost {
struct blank;
} // namespace boost
#endif // BOOST_BLANK_FWD_HPP