New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/25580#issuecomment-708888843

Comment:
I didn't catch it in my earlier review, but the template [failed to cross-build the C extension](https://travis-ci.org/github/void-linux/void-packages/jobs/735919542#L606) because the host Python could not find numpy (native builds had no such issue). Setting `build_helper="numpy"` in 0ae0bf920a7a9fbbd8f6e362beb3bf23e1af522d automatically adds `python3-numpy` to `hostmakedepends` and, when cross buliding, adds the `python3-numpy` to `makedepends` and sets up the environment to make sure the compilers correctly find the target headers and libraries. The package now cross-builds the C extension.