Fix compilation with clang-15

[dimula73]

std::unary_function and std::binary_function are removed from the standard in C++17.

[glenfe]

I think we should just define these unconditionally for now. I can take care of it, for 1.83. If needed we can provide a patch for clang 15 users for 1.82 on the website.

[alvinhochun]

For reference, BOOST_NO_CXX98_FUNCTION_BASE is defined in:
boostorg/config@0e364ef
boostorg/config#430
boostorg/config#440

[JIghtuse]

Please fix it, it breaks parts of boost which depend on functional. See this example with multi_array: user needs to pass weird -D_HAS_AUTO_PTR_ETC=0 to fix compilation with Clang + libc++.