`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++`
{
    if (strFlags.empty()) {
        return 0;
    }
    unsigned int flags = 0;
    std::vector<std::string> words;
    boost::algorithm::split(words, strFlags, boost::algorithm::is_any_of(","));
    for (const std::string& word : words)
    {
        if (!mapFlagNames.count(word))
            BOOST_ERROR("Bad test: unknown verification flag '" << word << "'");
        flags |= mapFlagNames[word];
    }
    return flags;
}
std::string FormatScriptFlags(unsigned int flags)