[boost] [type_traits] Reverting support for clang 3.0 intrinsics

Hi, As discussed here: http://lists.boost.org/Archives/boost/2011/06/182574.php Changeset #72423 is incorrect, since it's based on the clang version number which is not a reliable indicator of feature support: https://svn.boost.org/trac/boost/changeset/72423 So I think it should be reverted. Daniel