While fuzzing the RPC interface I stumbled upon a signed integer overflow in `CTxMemPool::PrioritiseTransaction(…)` which is reachable via the following two `prioritisetransaction` RPC calls:

```
$ ./autogen.sh
$ CC=clang CXX=clang++ ./configure --with-sanitizers=address,undefined
$ make
$ UBSAN_OPTIONS="print_stacktrace=1" src/bitcoind &
$ src/bitcoin-cli prioritisetransaction cafebabecafebabecafebabecafebabecafebabecafebabecafebabecafebabe 0 -9123456789123456789
$ src/bitcoin-cli prioritisetransaction cafebabecafebabecafebabecafebabecafebabecafebabecafebabecafebabe 0 -9123456789123456789
txmempool.cpp:832:15: runtime error: signed integer overflow: -9123456789123456789 + -9123456789123456789 cannot be represented in type 'long'
    #0 0x5581f3e69c3c in CTxMemPool::PrioritiseTransaction(uint256 const&, long const&) src/txmempool.cpp:832:15
    #1 0x5581f3c93852 in prioritisetransaction()::$_6::operator()(RPCHelpMan const&, JSONRPCRequest const&) const src/rpc/mining.cpp:470:36
…

SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior txmempool.cpp:832:15
```

Nothing high priority of course, but still worth fixing :)
{
        
        if (queuedTx.empty()) {
            return;
        }
        for (auto const &tx : vtx) {
            auto it = queuedTx.find(tx->GetHash());
            if (it != queuedTx.end()) {
                cachedInnerUsage -= RecursiveDynamicUsage(*it);
                queuedTx.erase(it);
            }
        }
    }
    
    void removeEntry(indexed_disconnected_transactions::index<insertion_order>::type::iterator entry)
    {
        cachedInnerUsage -= RecursiveDynamicUsage(*entry);
        queuedTx.get<insertion_order>().erase(entry);
    }
    void clear()
    {
        cachedInnerUsage = 0;
        queuedTx.clear();
    }
};
#endif