`validation_flush_tests/getcoinscachesizestate` fails on RISCV-64 on master:
```
Running 394 test cases...
test/validation_flush_tests.cpp(99): error: in "validation_flush_tests/getcoinscachesizestate": check chainstate.GetCoinsCacheSizeState(tx_pool, MAX_COINS_CACHE_BYTES, 0) == CoinsCacheSizeState::OK has failed [1 != 0]

*** 1 failure is detected in the test module "Bitcoin Core Test Suite"
```
Haven't investigated why, yet. Apart from the architecture it could also be some dependency version causing the problem (this is a fedora rawhide install with very new versions of everything including gcc and boost).

Edit: see below, this is likely due to a newer `libstdc++`
{
    CMutableTransaction mtx;
    mtx.nVersion = 1;
    CKey key;
    key.MakeNewKey(true); 
    FillableSigningProvider keystore;
    BOOST_CHECK(keystore.AddKeyPubKey(key, key.GetPubKey()));
    CKeyID hash = key.GetPubKey().GetID();
    CScript scriptPubKey = CScript() << OP_0 << std::vector<unsigned char>(hash.begin(), hash.end());
    std::vector<int> sigHashes;
    sigHashes.push_back(SIGHASH_NONE | SIGHASH_ANYONECANPAY);
    sigHashes.push_back(SIGHASH_SINGLE | SIGHASH_ANYONECANPAY);
    sigHashes.push_back(SIGHASH_ALL | SIGHASH_ANYONECANPAY);
    sigHashes.push_back(SIGHASH_NONE);
    sigHashes.push_back(SIGHASH_SINGLE);
    sigHashes.push_back(SIGHASH_ALL);
    
    for(uint32_t ij = 0; ij < 4500; ij++) {
        uint32_t i = mtx.vin.size();
        uint256 prevId;
        prevId.SetHex("0000000000000000000000000000000000000000000000000000000000000100");
        COutPoint outpoint(prevId, i);
        mtx.vin.resize(mtx.vin.size() + 1);
        mtx.vin[i].prevout = outpoint;
        mtx.vin[i].scriptSig = CScript();