Sorry, this is a big-bang PR implementing:

• func Load() (ok bool, err error) to ease the integration in dd-trace-go so that we can distinguish the different possible error cases:
  • Panic errors that must be used to gracefully abort the caller and prevent it from continuing. Such errors are represented by the new PanicError error type.
  • Unsupported target OS and/or architecture, which must be handled as an informative error, is worth logging to the user, and prevents the caller from continuing. This error is represented by the new UnsupportedTarget error type.
  • Every other unexpected error that can possible happen is returned as-is, but ok is false, so that the caller knows it cannot use the package.
  • Informative errors, about internal non-critical failures, can also happen (eg. if os.Remove fails removing the temporary files), and are returned as-is, but with ok being true so that the caller can log the error and continue its startup.
  • The dd-trace-go integration of this PR can be found here appsec: integrate the new purego-based go-libddwaf dd-trace-go#2090
  • Note that Health() has been kept for the sake of simplicity health-checking cases such as in the tests, where it returns the Load() error only if ok is false, meaning that go-libddwaf is not healthy.
• Simplified build tags, removed everywhere it was possible, down to purego which isn't properly stubbed for unsupported targets and which we stub ourselves at our level in the new waf_dl_unsupported.go file.