`<ranges>`: `ranges::equal` does not work for ranges with integer-class `range_difference_t`

[JMazurkiewicz]

Repro:

#include <algorithm>
#include <ranges>

using namespace std;

void f() {
  auto v = views::iota(0ull, 5ull) | views::stride(2); // range_difference_t<v> == _Unsigned128
  auto w = views::iota(0ull, 5ull) | views::stride(2);
  (void)ranges::equal(v, w);
}

Expected: correct compilation
Got: error (see link below)
Compiler explorer: https://godbolt.org/z/crcbMfY7z
Discovered while implementing #2923

[StephanTLavavej]

Yep, this seems like a bug in _Equal_count, with a very simple fix. A brief search indicated no other occurrences of integral _Size so hopefully this is the only one.