message: Fix separator concatenation logic.
diff: @@ -77,7 +77,7 @@ std::string ParameterNameStyleRule::ViolationMsg(absl::string_view symbol_type,
  std::string bit_list;
  for (const auto& b : kBitNames) {
  if (allowed_bitmap & b.first) {
  - if (bit_list.empty()) bit_list.append(" or ");
  + if (!bit_list.empty()) bit_list.append(" or ");
  bit_list.append(b.second);
  }
  }
  