Correct compilation
./b2 variant=debug,release --layout=versioned toolset=clang cxxflags="-fPIC -std=c++11 -stdlib=libc++ -arch i386 -arch x86_64" linkflags="-std=c++11 -stdlib=libc++ -arch i386 -arch x86_64" threading=multi link=shared --stagedir=stage_darwin_intel_shared_mt stage