High memory usage for very big directories

### Environment

  * OS Version: Windows 10 (1903)
  * Node.js Version: 12.4.0

### Actual behavior

```
FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory
```

### Expected behavior

I see entries.

### Steps to reproduce

1. Find directory with 2-4kk entries.
2. Run `fast-glob` with `**` pattern
