Revert "use lexicographical_compare_three_way"

This reverts commit 54038d2.

src/test/fuzz/feefrac.cpp

@@ -7,7 +7,6 @@
 #include <test/fuzz/fuzz.h>
 #include <test/fuzz/util.h>
 
-#include <algorithm>
 #include <compare>
 #include <cstdint>
 #include <iostream>
@@ -45,6 +44,15 @@ std::array<uint32_t, 4> Mul128(uint64_t a, uint64_t b)
     return ret;
 }
 
+/* comparison helper for std::vector */
+std::strong_ordering compare_arrays(const std::array<uint32_t, 4>& a, const std::array<uint32_t, 4>& b) {
+    for (size_t i = 0; i < a.size(); ++i) {
+        if (a[i] < b[i]) return std::strong_ordering::less;
+        if (a[i] > b[i]) return std::strong_ordering::greater;
+    }
+    return std::strong_ordering::equal;
+}
+
 std::strong_ordering MulCompare(int64_t a1, int64_t a2, int64_t b1, int64_t b2)
 {
     // Compute and compare signs.
@@ -64,9 +72,9 @@ std::strong_ordering MulCompare(int64_t a1, int64_t a2, int64_t b1, int64_t b2)
     auto mul_abs_a = Mul128(abs_a1, abs_a2);
     auto mul_abs_b = Mul128(abs_b1, abs_b2);
     if (sign_a < 0) {
-        return std::lexicographical_compare_three_way(mul_abs_b.begin(), mul_abs_b.end(), mul_abs_a.begin(), mul_abs_a.end());
+        return compare_arrays(mul_abs_b, mul_abs_a);
     } else {
-        return std::lexicographical_compare_three_way(mul_abs_a.begin(), mul_abs_a.end(), mul_abs_b.begin(), mul_abs_b.end());
+        return compare_arrays(mul_abs_a, mul_abs_b);
     }
 }