Merge bitcoin/bitcoin#34939: fuzz: Use CAmount for storing best_waste

890a09b fuzz: Use CAmount for storing best_waste (Ava Chow)

Pull request description:

  Waste is a CAmount, which is an int64_t. This will overflow an int, so `best_waste` should also be a `CAmount`.

  Fixes #34936

ACKs for top commit:
  murchandamus:
    ACK 890a09b
  furszy:
    ACK 890a09b

Tree-SHA512: c6c4f530960f038675d4549c2285c6a4a828099a631486e317ec1215d89688ce109304654a95800978607c360c2ed34803523f5c56ebf7c2324ca095f87825b8

Author: fanquake

src/wallet/test/fuzz/coinselection.cpp

@@ -275,7 +275,7 @@ FUZZ_TARGET(bnb_finds_min_waste)
 
     // Brute force optimal solution (lowest waste, but cannot be superset of another solution)
     std::vector<uint32_t> solutions;
-    int best_waste{std::numeric_limits<int>::max()};
+    CAmount best_waste{std::numeric_limits<int64_t>::max()};
     int best_weight{std::numeric_limits<int>::max()};
     for (uint32_t pattern = 1; (pattern >> num_groups) == 0; ++pattern) {
         // BnB does not permit adding more inputs to a solution, i.e. a superset of a solution cannot ever be a solution.