[Issue 18896] extern(C++) always mangles classes as pointer

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18896

--- Comment #1 from Mathias LANG <pro.mathias.lang at gmail.com> ---
Renamed to make it a bit more generic.
This is also a problem when `ref` is used for passing the class around.
E.g. `foo(MyClass&)` cannot be represented in D, which is very limiting.

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