message: Improve logging accuracy
diff: @@ -158,7 +158,10 @@ static void DescribeFileUnit(Stream &s, swift::FileUnit *file_unit) {
  } break;
  case swift::FileUnitKind::SerializedAST:
  case swift::FileUnitKind::ClangModule: {
  - s.PutCString("SerializedAST, ");
  + if (file_unit->getKind() == swift::FileUnitKind::SerializedAST)
  + s.PutCString("Serialized Swift AST, ");
  + else
  + s.PutCString("Clang module, ");
  swift::LoadedFile *loaded_file = llvm::cast<swift::LoadedFile>(file_unit);
  s.Printf("filename = '%s'", loaded_file->getFilename().str().c_str());
  } break;
  