In early C++11 standard drafts, std::function derived from std::unary_function...

In early C++11 standard drafts, std::function derived from std::unary_function or std::binary_function if there was only one (or two) parameters. Before C++11 shipped, this restiction was lifted, but libc++ still does this (which is fine). However, the tests still check for this outdated requiremnt. Change then to check for the nested typedefs instead (which are still required by the standard). No change to the library.

llvm-svn: 225430