Fix sycl-time-trace-actual link-mode failure in Self build / Build + LIT

[Copilot]

The failing job was caused by a single Clang driver test: Clang :: Driver/sycl-time-trace-actual.cpp.
Its compile+link SYCL path (--offload-new-driver) emitted wrapper calls to __sycl_register_lib / __sycl_unregister_lib, but the test links without SYCL runtime and failed with undefined references.

• Root cause

  • Test 3 in sycl-time-trace-actual.cpp performs a real link step.
  • The offload wrapper object now expects SYCL registration symbols during link, which are not available in this test environment.

• Targeted fix

  • Added local C-linkage stubs for the two SYCL registration hooks directly in the test source so link-mode succeeds without pulling in runtime libraries.
  • Kept the rest of the test logic and expectations unchanged (trace file generation/naming behavior remains the same).

• Patch excerpt

  extern "C" void __sycl_register_lib(void *) {}
  extern "C" void __sycl_unregister_lib(void *) {}
  
  int main() {
    return 0;
  }