Standard library function `fmt::ArgumentV1::<'a>::as_usize` does not compile

Related to https://github.com/model-checking/rmc/issues/109

```
thread 'rustc' panicked at 'Expected fat pointer, got
            Pointer { typ: StructTag("tag-fmt::Opaque") }
            in function fmt::ArgumentV1::<'a>::as_usize',
            compiler/rustc_codegen_llvm/src/gotoc/place.rs:96:13
```