won't compile on musl-based system

I tried compiling this project with `cargo build --release` and got the following error:
```
error: cannot produce proc-macro for `cpp_macros v0.4.0` as the target `x86_64-unknown-linux-musl` does not support these crate types
```

Result of uname -a:
`Linux void 4.19.66_1 #1 SMP PREEMPT Sun Aug 11 20:25:01 UTC 2019 x86_64 GNU/Linux`