message: [tstring] In `SerializeToTString()` use `SerializeWithCachedSizesToArray()`.
  This avoids the need to calculate the serialized size of the message twice, and matches the behavior of `MessageLite::SerializeToString()`.
diff: @@ -91,7 +91,8 @@ inline bool SerializeToTString(const protobuf::MessageLite& proto,
  tstring* output) {
  size_t size = proto.ByteSizeLong();
  output->resize_uninitialized(size);
  - return proto.SerializeToArray(output->data(), static_cast<int>(size));
  + return proto.SerializeWithCachedSizesToArray(
  + reinterpret_cast<uint8*>(output->data()));
  }
  inline bool ParseFromTString(const tstring& input,
  