Support for removed function objects in C++17

std::unary_function and std::binary_function are removed in C++17, and
Visual C++ is the first compiler to do this (when the appropriate macro
is defined). I'm not sure what the long term solution should be, but
hopefully this will work for now.

test/compile_time.hpp

@@ -10,7 +10,9 @@
 template <class T>
 void compile_time_tests(T*)
 {
+#if !defined(_HAS_AUTO_PTR_ETC) || _HAS_AUTO_PTR_ETC
     BOOST_STATIC_ASSERT((boost::is_base_and_derived<
         std::unary_function<T, std::size_t>, BOOST_HASH_TEST_NAMESPACE::hash<T> >::value));
+#endif
 }