New review comment by reedts on void-packages repository

https://github.com/void-linux/void-packages/pull/43377#discussion_r1161993018

Comment:
Yes that would work too. However, when using `build_style=gnu-makefile` you'd get a build error because it will try to build `make all`, which in this case does not exist. If you want to use `gnu-makefile` I'd suggest to unset the build function like this:

```sh
do_build() {
    :
}
```