feefrac test: avoid integer overflow (bugfix)

Author: sipa

src/test/fuzz/feefrac.cpp

@@ -220,9 +220,9 @@ FUZZ_TARGET(feefrac_mul_div)
         assert(res == res_fee);
 
         // Compare approximately with CFeeRate.
-        if (mul64 <= std::numeric_limits<int64_t>::max() / 1000 &&
-            mul64 >= std::numeric_limits<int64_t>::min() / 1000 &&
-            quot_abs <= arith_uint256{std::numeric_limits<int64_t>::max() / 1000}) {
+        if (mul64 < std::numeric_limits<int64_t>::max() / 1000 &&
+            mul64 > std::numeric_limits<int64_t>::min() / 1000 &&
+            quot_abs < arith_uint256{std::numeric_limits<int64_t>::max() / 1000}) {
             CFeeRate feerate(mul64, (uint32_t)div);
             CAmount feerate_fee{feerate.GetFee(mul32)};
             auto allowed_gap = static_cast<int64_t>(mul32 / 1000 + 3 + round_down);