[boost] [config] defect macro for chrono literals

boost.config defines BOOST_NO_CXX11_USER_DEFINED_LITERALS but I believe this defect macro could not be used for detecting chrono literals support. Should the new BOOST_NO_CXX14_CHRONO_LITERALS depend on the compiler or stdlib version? AFAIK chrono literals are available since gcc-4.9.3 (clang?, intel?, msvc?). Oliver