clang and __float128 bug/error

I've successfully compiled the current 3.3 branch of clang. But then C++ compilation of any file fails with the bug/error. Can that be fixed? ``` In file included from /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/iostream:39: In file included from /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/ostream:39: In file included from /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/ios:40: In file included from /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/bits/char_traits.h:40: In file included from /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/bits/stl_algobase.h:65: In file included from /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/bits/stl_pair.h:61: In file included from /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/bits/move.h:57: /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../include/c++/4.7/type_traits:256:39: error: use of undeclared identifier '__float128' struct __is_floating_point_helper<__float128> ^ 1 error generated. ```