[m-rev.] for post-commit review: fix some test failures in java grade

[Peter Wang]

On Thu, 04 Sep 2025 23:44:24 +0200 "Zoltan Somogyi" <zoltan.somogyi at runbox.com> wrote:
> For review by anyone.
> 
> Zoltan.

> Fix some Java/C# test case failures.
> 
> library/rtti_implementation.m:
>     Return zero arity for null TypeInfo.args arrays. This fixes the
>     failure of the hard_coded/pretty_printing test case in the Java grade,
>     and probably in the C# grade as well.
> 

I've made a similar change in type_desc.m

Peter