`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++`
pubkey3 = key3.GetPubKey();
    pubkey1L = key1L.GetPubKey();
    pubkey2L = key2L.GetPubKey();
    BOOST_CHECK(keystore.AddKeyPubKey(key1, pubkey1));
    BOOST_CHECK(keystore.AddKeyPubKey(key2, pubkey2));
    BOOST_CHECK(keystore.AddKeyPubKey(key1L, pubkey1L));
    BOOST_CHECK(keystore.AddKeyPubKey(key2L, pubkey2L));
    CScript scriptPubkey1, scriptPubkey2, scriptPubkey1L, scriptPubkey2L, scriptMulti;
    scriptPubkey1 << ToByteVector(pubkey1) << OP_CHECKSIG;
    scriptPubkey2 << ToByteVector(pubkey2) << OP_CHECKSIG;
    scriptPubkey1L << ToByteVector(pubkey1L) << OP_CHECKSIG;
    scriptPubkey2L << ToByteVector(pubkey2L) << OP_CHECKSIG;
    std::vector<CPubKey> oneandthree;
    oneandthree.push_back(pubkey1);
    oneandthree.push_back(pubkey3);
    scriptMulti = GetScriptForMultisig(2, oneandthree);
    BOOST_CHECK(keystore.AddCScript(scriptPubkey1));
    BOOST_CHECK(keystore.AddCScript(scriptPubkey2));
    BOOST_CHECK(keystore.AddCScript(scriptPubkey1L));
    BOOST_CHECK(keystore.AddCScript(scriptPubkey2L));
    BOOST_CHECK(keystore.AddCScript(scriptMulti));
    BOOST_CHECK(keystore.AddCScript(GetScriptForWitness(scriptPubkey1)));
    BOOST_CHECK(keystore.AddCScript(GetScriptForWitness(scriptPubkey2)));
    BOOST_CHECK(keystore.AddCScript(GetScriptForWitness(scriptPubkey1L)));
    BOOST_CHECK(keystore.AddCScript(GetScriptForWitness(scriptPubkey2L)));
    BOOST_CHECK(keystore.AddCScript(GetScriptForWitness(scriptMulti)));
    BOOST_CHECK(keystore2.AddCScript(scriptMulti));
    BOOST_CHECK(keystore2.AddCScript(GetScriptForWitness(scriptMulti)));
    BOOST_CHECK(keystore2.AddKeyPubKey(key3, pubkey3));
    CTransactionRef output1, output2;