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=""
```
{
    constexpr uint64_t min_disk_space = 52428800; 
    uint64_t free_bytes_available = fs::space(dir).available;
    return free_bytes_available >= min_disk_space + additional_bytes;
}
std::streampos GetFileSize(const char* path, std::streamsize max) {
    std::ifstream file(path, std::ios::binary);
    file.ignore(max);
    return file.gcount();
}
/**
 * Interpret a string argument as a boolean.
 *
 * The definition of atoi() requires that non-numeric string values like "foo",
 * return 0. This means that if a user unintentionally supplies a non-integer
 * argument here, the return value is always false. This means that -foo=false
 * does what the user probably expects, but -foo=true is well defined but does
 * not do what they probably expected.
 *
 * The return value of atoi() is undefined when given input not representable as
 * an int. On most systems this means string value between "-2147483648" and
 * "2147483647" are well defined (this method will return true). Setting
 * -txindex=2147483648 on most systems, however, is probably undefined.
 *
 * For a more extensive discussion of this topic (and a wide range of opinions
 * on the Right Way to change this code), see PR12713.
 */
static bool InterpretBool(const std::string& strValue)