No compiler error when attempting to use voidptr as type argument

Using `voidptr ` as a type argument does not cause a compiler error, even though it is invalid and causes a `BadImageFormatException` or `TypeLoadException` at runtime.

**Repro steps**

1. Use `voidptr` as a type argument, e.g:
```fs
let badList: voidptr list = []
printf "%A" badList
```
2. Compile.

**Expected behavior**

An error, preventing compilation. This happens in C# with `void*`.

**Actual behavior**

No compilation error, but errors at runtime.

**Known workarounds**

Don't try to use `voidptr` as a generic type argument.

**Related information**

* Operating system: Kubuntu 25.10
* .NET Runtime kind: .NET 10
* Editing Tools: JetBrains Rider 2025.3.1