`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++`
LOCK(cs_main);
    FillableSigningProvider keystore;
    CCoinsView coinsDummy;
    CCoinsViewCache coins(&coinsDummy);
    std::vector<CMutableTransaction> dummyTransactions = SetupDummyInputs(keystore, coins);
    CMutableTransaction t;
    t.vin.resize(1);
    t.vin[0].prevout.hash = dummyTransactions[0].GetHash();
    t.vin[0].prevout.n = 1;
    t.vin[0].scriptSig << std::vector<unsigned char>(65, 0);
    t.vout.resize(1);
    t.vout[0].nValue = 90*CENT;
    CKey key;
    key.MakeNewKey(true);
    t.vout[0].scriptPubKey = GetScriptForDestination(PKHash(key.GetPubKey()));
    std::string reason;
    BOOST_CHECK(IsStandardTx(CTransaction(t), reason));
    
    CAmount nDustThreshold = 182 * dustRelayFee.GetFeePerK()/1000;
    BOOST_CHECK_EQUAL(nDustThreshold, 546);
    
    t.vout[0].nValue = nDustThreshold - 1;
    reason.clear();
    BOOST_CHECK(!IsStandardTx(CTransaction(t), reason));
    BOOST_CHECK_EQUAL(reason, "dust");
    
    t.vout[0].nValue = nDustThreshold;
    BOOST_CHECK(IsStandardTx(CTransaction(t), reason));
    
    t.nVersion = -1;