The platform could be determined at runtime. Note that the string for the URL will be evaluated by the shell at runtime, so that could be used to preliminarily determine the platform.

The addon could either export a tiny shell function, or use something simple for now:

```
"https://scan.coverity.com/build_tool/cov-analysis-$([ `uname` = "Linux" ] && echo 'linux64' || echo 'macosx')-#{@config[:build_utility_version]}.tar.gz"
```