Rollup merge of #126717 - nnethercote:rustfmt-use-pre-cleanups, r=jieyouxu

Clean up some comments near `use` declarations

#125443 will reformat all `use` declarations in the repository. There are a few edge cases involving comments on `use` declarations that require care. This PR cleans up some clumsy comment cases, taking us a step closer to #125443 being able to merge.

r? ``@lqd``

compiler/rustc_codegen_ssa/src/mir/locals.rs

@@ -1,6 +1,7 @@
 //! Locals are in a private module as updating `LocalRef::Operand` has to
 //! be careful wrt to subtyping. To deal with this we only allow updates by using
 //! `FunctionCx::overwrite_local` which handles it automatically.
+
 use crate::mir::{FunctionCx, LocalRef};
 use crate::traits::BuilderMethods;
 use rustc_index::IndexVec;