While testing 17270 I noticed that master (bdda137878904e9401a84e308ac74c93c2ef87c1) does not run on NetBSD. I assume this started after #17085 changed the fallback locale from `C` to `C.UTF-8`. There doesn't seem to be a `C.UTF-8` locale on NetBSD.

```bash
src/bitcoind
terminate called after throwing an instance of 'std::runtime_error'
  what():  locale::facet::_S_create_c_locale name not valid
Abort trap (core dumped)
```

`LC_ALL=C src/bitcoind` works, `LC_ALL=en_US.UTF-8 src/bitcoind` does not.

```bash
locale
LANG=""
LC_CTYPE="en_US.UTF-8"
LC_COLLATE="C"
LC_TIME="C"
LC_NUMERIC="C"
LC_MONETARY="C"
LC_MESSAGES="C"
LC_ALL=""
```
{
    if (val.isBool() && !(flags & ArgsManager::ALLOW_BOOL)) {
        error = strprintf("Negating of -%s is meaningless and therefore forbidden", key);
        return false;
    }
    return true;
}
namespace {
fs::path StripRedundantLastElementsOfPath(const fs::path& path)
{
    auto result = path;
    while (result.filename().string() == ".") {
        result = result.parent_path();
    }
    assert(fs::equivalent(result, path));
    return result;
}
} 
ArgsManager::ArgsManager() {}
ArgsManager::~ArgsManager() {}