e7d72b6f53
1. Handle `sigsetjmp` platform differences:
- Separate `sigsetjmp` linkage to platform-specific files.
- Use `__sigsetjmp` on Linux to handle `sigsetjmp` being a macro.
- Maintain original implementation for Darwin.
2. Ensure linking of required libs:
- Explicitly link against fundamental libs (e.g., libm, libatomic).
- Address the fact that typical Linux linkers don't link these by
default.