Extending call_args when specialising DFuns

[ÉRDI Gergő]

On Mon, 2 May 2022, Simon Peyton Jones wrote:

> This is really a GHC bug already, albeit one that is hard to provoke.  Would you like
> to open a ticket and add the fix?

I'm happy to provide a patch (and also fix the comment referencing 
GHC.Core.Unfold.specUnfolding), but I don't think I'll be able to provide 
a test case for it, because, like you said, it's hard to provoke.