Possible `Nan::Callback` leak in async `inquire()` (the `found` callback)

[OvOhao]

Possible Nan::Callback leak in async inquire() (the found callback)

I found a possible native heap leak in the async inquire() path. InquireWorker
stores a second found callback that the base Nan::AsyncWorker does not own, and the
subclass destructor never frees it.

File: src/linux/DeviceINQ.cc

Functions: InquireWorker, DeviceINQ::Inquire

class InquireWorker : public Nan::AsyncWorker {
 public:
  InquireWorker(Nan::Callback* found, Nan::Callback *callback)
    : Nan::AsyncWorker(callback), found(found) {}
  ~InquireWorker() {}                 // does not delete found
  ...
 private:
    Nan::Callback* found;
};

NAN_METHOD(DeviceINQ::Inquire) {
  ...
  Nan::Callback *found = new Nan::Callback(info[0].As<Function>());
  Nan::Callback *callback = new Nan::Callback(info[1].As<Function>());
  Nan::AsyncQueueWorker(new InquireWorker(found, callback));
}

Nan::AsyncWorker's base destructor deletes only the callback it was constructed with.
found is a separate member and ~InquireWorker() is empty, so found (a heap
Nan::Callback retaining a v8::Persistent to the JS function) leaks on every
inquire() call.

Suggested fix: delete found; in ~InquireWorker(), or store found in an owning smart
pointer.