New comment by gcat432 on void-packages repository

https://github.com/void-linux/void-packages/pull/12189#issuecomment-499461490
Comment:
```
=> ERROR: crystal-0.29.0_1: cannot be cross compiled, exiting...
=> ERROR: crystal-0.29.0_1: FIXME: someone needs to sort out the llvm --cxxflags for cross building
```

See template.