Segmentation fault when mapping to adafruit-hat

When I'm trying this:
```rust
let mut config = LedMatrixOptions::new();
config.set_hardware_mapping("adafruit-hat");

println!("TOMB1");

let matrix = LedMatrix::new(Some(config));
```
the code segfaults. this is with the commit https://github.com/hzeller/rpi-rgb-led-matrix/commit/212b0bbccbbd9adacbf0d49b6c0adbaeb7e83422