Project whose path contains non-ASCII characters fails to build on Windows

### Steps to reproduce

A project produced with these steps built without any errors on Ubuntu 14.04 but failed on Windows 10.

1. Create a new project using `stack new test-project` in a directory whose name contains non-ASCII characters, such as `C:\Desktop\folderß\`. The project name itself doesn't have to contain non-ASCII characters.
2. Run command `stack build` inside `C:\Desktop\folderß\test-project\`.

### Expected

I expected stack to successfully build the project and not care about what directory it's in.

### Actual

The project was not successfully built, no binaries were produced.

```
$ stack build --verbose
```
[Output of `stack build --verbose` when building a project in a directory whose name contains non-ASCII characters on Windows](https://gist.github.com/mrbraitwistle/6eafa68030ac9ced0b53decf7bfe7e28)

### Stack version

```
$ stack --version
Version 1.2.0 x86_64 hpack-0.14.0
```

### Method of installation

Official binary, downloaded from https://docs.haskellstack.org/en/stable/install_and_upgrade, then upgraded using `stack upgrade`