addrman: change nid_type from int to int64_t

With nId being incremented for each addr received,
an attacker could cause an overflow in the past.
(https://bitcoincore.org/en/2024/07/31/disclose-addrman-int-overflow/)
Even though that attack was made infeasible by
rate-limiting (PR bitcoin#22387), to be on the safe side change the
type to an int64_t.

Author: mzumsande

src/addrman_impl.h

@@ -32,6 +32,13 @@ static constexpr int ADDRMAN_NEW_BUCKET_COUNT{1 << ADDRMAN_NEW_BUCKET_COUNT_LOG2
 static constexpr int32_t ADDRMAN_BUCKET_SIZE_LOG2{6};
 static constexpr int ADDRMAN_BUCKET_SIZE{1 << ADDRMAN_BUCKET_SIZE_LOG2};
 
+/**
+ * User-defined type for the internally used nIds
+ * This used to be int, making it feasible for attackers to cause an overflow,
+ * see https://bitcoincore.org/en/2024/07/31/disclose-addrman-int-overflow/
+ */
+using nid_type = int64_t;
+
 /**
  * Extended statistics about a CAddress
  */