Fix build on macOS

[aheck]

No description provided.

[Aetf]

Thanks for the PR!

Ideally, this should coordinate with windows build fixes to have compiler/OS specific in a single place.

CI needs to be extended to test on macOS (and windows considering #25). Otherwise, I may accidentally break builds on those platforms in the future as I can't test them locally. A quick search suggests that Github Action has windows and macOS environments. If you could also set up those that'd be great. Otherwise, I need to find a time to sit down and look into these...

[aheck]

Didn't use GitHub Actions before but I will look into it.

[aheck]

I got it running as a matrix build in https://github.com/aheck/libtsm/tree/macos-github-action. When I have time again I will clean it up a bit and add the final result to this PR.

From what I have seen so far it should be no problem to add Windows as the third build platform later on. But since Windows is probably a bit more work than macOS I think it is better to add Windows in a separate PR.

One question: When testing on my machines I only build the static version of the library because I prefer it over dynamic linking. This workflow builds the dynamic library and so I stumbled over the linker script that I never took notice of before: src/tsm/libtsm.sym. clang doesn't know the option --version-script that gets set in src/tsm/CMakeLists.txt and so the build failed. I disabled this option for compilers other than gcc. But do we really need this linker script? We already have the SHL_EXPORT macro to control the visibility of functions.

[aheck]

I updated it. The PR now includes the extended GitHub Actions workflow that builds on Ubuntu as well as on macOS.

Let me know what you think.

[Aetf]

Thanks!