Remove std::binary_function from Registration

[greenbrettmichael]

Removed std::binary_function from Registration library to support C++17, this change should be reverse compatible

[taketwo]

@SergioRAgostinho Should be safe to include in 1.9.0 I think.

[SergioRAgostinho]

@taketwo safe to assume it breaks the ABI right?

[taketwo]

I don't think so, it was a pure meta-programming gizmo. Here is how binary_function looks like in standard library (7.3.0):

template<typename _Arg1, typename _Arg2, typename _Result>
struct binary_function
{
/// @c first_argument_type is the type of the first argument
typedef _Arg1    first_argument_type;·
/// @c second_argument_type is the type of the second argument
typedef _Arg2    second_argument_type;
/// @c result_type is the return type
typedef _Result  result_type;
};

[SergioRAgostinho]

Thank you both.

Edit: Forgot to squash 🤦‍♂️ sorry