mkdir: no error when no path is provided

```
❯ /usr/bin/mkdir ; printf '%s\n' "${?:?}"
/usr/bin/mkdir: missing operand
Try '/usr/bin/mkdir --help' for more information.
1

❯ coreutils mkdir ; printf '%s\n' "${?:?}"
0
```

`mkdir` should not exit with a 0 exit code when no path is provided, and an error/help message should be printed.