[clang-c] using clang_getNullCursor from Java causes munmap_chunk(): invalid pointer on exit

Hi,

I'm making Java bindings for clang-c and have ran into an issue wherein using the `clang_getNullCursor` function will cause a `munmap_chunk(): invalid pointer` error on exit.

e.g:

```java
public class Test
{
public static void main(String[] args)
{
Index_h index = Index_h.INSTANCE;

CXCursor cursor = index.clang_getNullCursor();

NativeEnum32 kindField = cursor.getField(0);

System.out.println(kindField.get());

System.out.println(index.clang_isReference(CXCursorKind.CXCursor_ObjCSuperClassRef));
}
}
```

prints

```
CXCursor_FirstInvalid
1
munmap_chunk(): invalid pointer
```

If I comment out the clang-c `clang_getNullCursor` function call and related code, leaving only clang_isReference, this does not happen.

Is this some kind of bad interaction between clang-c and the JVM?

Clang Version is 21.1.8