Fix unwanted "Available on XX-bit only" in libcore integers Fixes rust-lang/rust#149786. The problem came from: <img width="754" height="734" alt="image" src="https://github.com/user-attachments/assets/c251326f-8640-420d-bc4c-a3246390ea67" /> The `doc_cfg` feature picks the `cfg` as it should. If we don't want it, we simply need to disable the feature on it. With this fix, no more `cfg` annotations: <img width="860" height="590" alt="image" src="https://github.com/user-attachments/assets/da793590-bf43-4874-94e1-a56809938420" /> r? @Urgau