Auto merge of rust-lang#57138 - matthiaskrgr:clippy, r=oli-obk

submodules: update clippy from fc24fce to 721f688

Fixes clippy toolstate.

Changes:
````
rustup rust-lang#57069
Rustfmt.
fix breakage from rust-lang#57088
fix a couple of ftrivial typos (NFC).
update CARGO_CLIPPY_HELP string to suggest tool lints.
rustc_tools_util: add readme
rustc_tool_utils: expand Cargo.toml with a few keywords in preparation for crates.io release
Fix macro detection in `empty_loop`.
Changed `macro_backtrace()` to `in_macro()`.
Fix lint detection on macro expansion.
````

r? @oli-obk

Author: bors