Can't compile with node12

## What Happens?

```
CXX(target) Release/obj.target/rocketmq/src/rocketmq.o
../src/rocketmq.cpp:42:116: error: too few arguments to function call, single argument 'context' was not specified
Nan::Set(target, Nan::New("macosDLOpen").ToLocalChecked(), Nan::New(DLOpen)->GetFunction());
```


## Minimum Showcase (Required)

> npm install --save apache-rocketmq with node v12

## Context

- **Node Version**: 12
- **SDK Version**: latest
- **Platform**: macos