message: we know the compiler will be g++ if it's gnu, but don't run for clang
diff: // workaround missing "is_trivially_copyable" in g++ < 5.0
  // From: https://stackoverflow.com/questions/25123458/is-trivially-copyable-is-not-a-member-of-std
  -#if __GNUG__ && __GNUC__ < 5
  +#if !__clang__ && __GNUC__ < 5
  #define OSP_IS_TRIVIALLY_COPYABLE(T) std::has_trivial_copy_constructor<T>::value
  #else
  #define OSP_IS_TRIVIALLY_COPYABLE(T) std::is_trivially_copyable<T>::value
  