message: Fix core::hint::black_box support
diff: @@ -689,6 +689,9 @@ fn is_fat_ptr<'tcx>(
  asm_str_style: _,
  } = asm;
  match &*asm_code.as_str() {
  + "" => {
  + // Black box
  + }
  cpuid if cpuid.contains("cpuid") => {
  crate::trap::trap_unimplemented(
  fx,
  