[boost] Should the clang, c++11 and libstdc++ configuration supported?

Hi, clang compiler is not delivered with a C++11 standard library. When compiling on c++11 mode, some boost libraries (in particular, Boost.Thread, Boost.SmartPtr, Boost.Test) are expecting to have a C++11 standard library. This mean that the user needs to install the latest version of libc++. Could we state clearly in the release notes if the combination clang+ -std=c++11 + libstdc++ is not supported. Otherwise these libraries should update their code so that the user can use this combination. Best, Vicente