You will need to make your own macro to do conditional compilation (or somehow control it with your build system). For instance:
#ifdef MYPROJ_HAS_BOOST
# include <boost/filesystem.hpp>
#endif
Then compile with -DMYPROJ_HAS_BOOST(or not).
BOOST_VERSION - Boost, , Boost. <boost/version.hpp> , Boost, , , .
#include <boost/version.hpp , ; , Boost .