CXXD_SHARED_MUTEX_HEADER — The shared mutex header file name.
// In header: <boost/cxx_dual/impl/shared_mutex.hpp> CXXD_SHARED_MUTEX_HEADER
The object-like macro expands to the include header file designation for the shared mutex header file. The macro is used with the syntax: #include CXXD_SHARED_MUTEX_HEADER
