Unicode in package name causes build failure

When I named my package `Query书法字典`, reading the generated paths module goes wrong:

```
# cabal new-build all
Build profile: -w ghc-8.6.3 -O1
In order, the following will be built (use -v for more details):
- Query书法字典-0.1.0.0 (exe:Query书法字典) (first run)
/home/edsko/personal/doc/calligraphy/Query书法字典/dist-newstyle/build/x86_64-linux/ghc-8.6.3/Query书法字典-0.1.0.0/x/Query书法字典/build/Query书法字典/autogen/Paths_Query书法字典.hs: hGetContents: invalid argument (invalid byte sequence)
```