in dub single file build how to pass "-J<dir>" options?

[mw]

I have example.d:

```
#!/usr/bin/env dub

/+dub.sdl:
dependency "tkd" version="~>1.1.14"
+/
...
```

$ dub build --single example.d

...
Error: need `-J` switch to import text file `folder_page.png`


I'm wondering how to pass  "-J<dir>" options?


BTW, for such single file build, do I have to use dub? is there 
another way to just use dmd?

Thanks.