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_mir_transform/src/unreachable_enum_branching.rs

@@ -1,6 +1,5 @@
 //! A pass that eliminates branches on uninhabited or unreachable enum variants.
 
-use crate::MirPass;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_middle::bug;
 use rustc_middle::mir::patch::MirPatch;
@@ -12,6 +11,8 @@ use rustc_middle::ty::layout::TyAndLayout;
 use rustc_middle::ty::{Ty, TyCtxt};
 use rustc_target::abi::{Abi, Variants};
 
+use crate::MirPass;
+
 pub struct UnreachableEnumBranching;
 
 fn get_discriminant_local(terminator: &TerminatorKind<'_>) -> Option<Local> {