Add support for building with clang/libcxx.
Add support for building with clang/libcxx.

kamilzubair/ChaiScript,bradparks/ChaiScript__cplusplus_scripting_language,kamilzubair/ChaiScript,bradparks/ChaiScript__cplusplus_scripting_language,kamilzubair/ChaiScript,bradparks/ChaiScript__cplusplus_scripting_language