[libc++] `tuple<>` cannot be compared with `array<T, 0>`

The following should be well-formed since C++23.

```cpp
#include <tuple>
#include <array>

int main() {
  std::array<int, 0> a;
  std::tuple<> t;
  auto eq = (t == a);
  auto cmp = (t <=> a);
}
```
https://godbolt.org/z/T9zME3x6v