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.
// Copyright (C) 2001-2003
// William E. Kempf
//
// 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_ONCE_WEK080101_HPP
#define BOOST_ONCE_WEK080101_HPP
#include <boost/thread/detail/config.hpp>
#if defined(BOOST_HAS_PTHREADS)
# include <pthread.h>
#endif
namespace boost {
#if defined(BOOST_HAS_PTHREADS)
typedef pthread_once_t once_flag;
#define BOOST_ONCE_INIT PTHREAD_ONCE_INIT
#elif (defined(BOOST_HAS_WINTHREADS) || defined(BOOST_HAS_MPTASKS))
typedef long once_flag;
#define BOOST_ONCE_INIT 0
#endif
void BOOST_THREAD_DECL call_once(void (*func)(), once_flag& flag);
} // namespace boost
// Change Log:
// 1 Aug 01 WEKEMPF Initial version.
#endif // BOOST_ONCE_WEK080101_HPP