Utility blocks when MIDI device is in use by another process

The utility blocks for no apparent reason when the MIDI device is in use by another process. The culprit seems to be line 30 in `midi.c`:
```r = snd_rawmidi_open(&handle_in, &handle_out, device, 0);```

If `SND_RAWMIDI_NONBLOCK` is set as the flags, then the utility properly exits with a human readable error:
```r = snd_rawmidi_open(&handle_in, &handle_out, device,  SND_RAWMIDI_NONBLOCK );```