<ranges>: Fix cartesian_product_view::size in debug mode

[JMazurkiewicz]

Per [range.cartesian.view]/9-10:

Let p be the product of the sizes of all the ranges in bases_.
Preconditions: p can be represented by the return type.

Currently cartesian_product_view::size may fail when p can be represented by return type:

#include <ranges>

using namespace std;

int main() {
  const auto r1 = views::repeat(0, (numeric_limits<ptrdiff_t>::max)());
  const auto r2 = views::repeat(1, 0);
  (void)views::cartesian_product(r1, r1, r1, r2).size(); // FAIL!
}

Obviously 0 can be represented by any unsigned integral type. This PR fixes this bug.

[StephanTLavavej]

I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

[StephanTLavavej]

Thanks for fixing this corner case! 0️⃣ ✖️ ♾️