bug#40825: Teeworlds fails to load sound files

[pkill9]

I've attached a log.

It seems to fail to load all the sound files, e.g.
```
[2020-04-24 19:09:35][sound/wv]: failed to open audio/music_menu.wv:
can't open file
```.

I don't think it is failing to find them, because they are in
<teeworlds-package>/share/teeworlds/data/audio, and it successfully
finds another file in the data subdirectory from seeing that log:
```
[2020-04-24 19:09:35][datafile]: loading.
filename='ui/themes/winter_night.map'
```

log.log
Description: Text Data