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=""
```
{
    LOCK(cs_args);
    m_network = network;
}
bool ArgsManager::ParseParameters(int argc, const char* const argv[], std::string& error)
{
    LOCK(cs_args);
    m_settings.command_line_options.clear();
    for (int i = 1; i < argc; i++) {
        std::string key(argv[i]);
#ifdef MAC_OSX
        
        
        
        
        if (key.substr(0, 5) == "-psn_") continue;
#endif
        if (key == "-") break; 
        std::string val;
        size_t is_index = key.find('=');
        if (is_index != std::string::npos) {
            val = key.substr(is_index + 1);
            key.erase(is_index);
        }
#ifdef WIN32
        key = ToLower(key);