Output file with path containing non-Latin Unicode characters on Windows

I've noticed some unusual behavior on Windows with output file paths containing non-Latin Unicode characters:

### Non-Latin characters in the output filename
```
$ brotli.exe -o "Lietuvių Kalbos Žodynu.br" "Hello.txt"
```
The command works, but the output filename is `Lietuviu Kalbos Žodynu.br`, not `Lietuvių Kalbos Žodynu.br`, as expected. (notice "u" versus "ų")

### Non-Latin characters in the name of the directory containing the output file
```
$ brotli.exe -o "Lietuvių Kalbos Žodynu\Hello.br" "Hello.txt"
```
the command fails with output:
```
failed to open output file [Lietuviu Kalbos Äodynu\Hello.br]: No such file or directory
```

By contrast, using these same non-Latin characters in the input path seems to work fine. And the problem doesn't seem to occur on MacOS.