Buffer api error since 13.3.0

Full detail:
https://github.com/node-ffi-napi/node-ffi-napi/issues/48#issuecomment-569230911

on 13.30 and after:
```
'node example/abs.js' terminated by signal SIGSEGV (Address boundary error)
```

on master
```console
terminated by signal SIGILL (Illegal instruction)
```

cc @nodejs/v8 @nodejs/n-api 