Reformat use declarations.

The previous commit updated `rustfmt.toml` appropriately. This commit is
the outcome of running `x fmt --all` with the new formatting options.

compiler/rustc_lint/src/map_unit_fn.rs

@@ -1,13 +1,11 @@
+use rustc_hir::{Expr, ExprKind, HirId, Stmt, StmtKind};
+use rustc_middle::query::Key;
+use rustc_middle::ty::{self, Ty};
+use rustc_session::{declare_lint, declare_lint_pass};
+
 use crate::lints::MappingToUnit;
 use crate::{LateContext, LateLintPass, LintContext};
 
-use rustc_hir::{Expr, ExprKind, HirId, Stmt, StmtKind};
-use rustc_middle::{
-    query::Key,
-    ty::{self, Ty},
-};
-use rustc_session::{declare_lint, declare_lint_pass};
-
 declare_lint! {
     /// The `map_unit_fn` lint checks for `Iterator::map` receive
     /// a callable that returns `()`.