[CPP] `Sys.getCwd()` returns wrong path if the path contains non-ascii chars

Following this openfl/lime/issues/1757 issue, I though I found a workaround, but it didn't work for cpp.

So, Lime structures get incorrect path to assets and the app crashes. Using `Sys.getCwd()` to get the correct path worked for my case only on HL. Trying it on `cpp` I still get the crash - non-ascii path results with wrong string returned by `Sys.getCwd()`.

```haxe
trace(Sys.getCwd());
```

what it should be
```
C:\game\export\windows\я\
```

but it is
```
C:\game\export\windows\╤П\
```

As was stated in similar issue #10859, tediously telling the users how to "properly start" the app is annoying.