`ld` linker needs more arguments starting with macOS 15

[olivergrabinski]

Issue description

When compiled on macOS 15, OpenVAF will fail at runtime with

ld: dynamic executables or dylibs must link with libSystem.dylib

which does not occur on earlier version of macOS.

Fix 1

Add arguments to explicitly point to the System library. In /openvaf/target/src/spec/aarch64_apple_darwin.rs

See this change.

Fix 2

Consider a unified approach for all platforms? Calling clang could be a cross-platform solution. But I am not aware of the reason why the linkers are called directly now.

See this change.

[arpadbuermen]

Make a pull requat for fix 1. When I return from holiday I will accept it. Can you check if the fixed openvaf works on older macs?
For now I would stick with MS linker under windows.

[olivergrabinski]

Sorry for the delay. After having a look, I noticed that I was using a newer llvm version... and when I specify llvm 15 I'm having a different problem. I will try to take a look and write an update here.

[arpadbuermen]

The merged LLVM18 version is in the llvm18 branch if you want to experiment. I am not in favor of using the llvm linker or clang for linking on all platforms because llvm is not the first choice on all platforms. For instance, windows users are more familiar with visual studio community edition and ms link.exe. If you have problems on, say macos platform, you should detect the platform, use the corresponding linker, call it, and feed it the correct set of options.

[robtaylor]

Fixed in #22