67fa36a9f2
move `readonly_write_lock` to perf [There haven't been any issues](https://github.com/rust-lang/rust-clippy/issues?q=is%3Aissue+readonly_write_lock) since its creation and it's a pretty useful lint I think, so I'd say it's worth giving it a try? Did a lintcheck run on 300 crates with no results, but I guess `RwLock` is usually not something that's used much in libraries. changelog: move [`readonly_write_lock`] to perf (now warn-by-default)