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_transmute/src/maybe_transmutable/mod.rs

@@ -4,11 +4,9 @@ pub(crate) mod query_context;
 #[cfg(test)]
 mod tests;
 
-use crate::{
-    layout::{self, dfa, Byte, Def, Dfa, Nfa, Ref, Tree, Uninhabited},
-    maybe_transmutable::query_context::QueryContext,
-    Answer, Condition, Map, Reason,
-};
+use crate::layout::{self, dfa, Byte, Def, Dfa, Nfa, Ref, Tree, Uninhabited};
+use crate::maybe_transmutable::query_context::QueryContext;
+use crate::{Answer, Condition, Map, Reason};
 
 pub(crate) struct MaybeTransmutableQuery<L, C>
 where
@@ -32,15 +30,12 @@ where
 // FIXME: Nix this cfg, so we can write unit tests independently of rustc
 #[cfg(feature = "rustc")]
 mod rustc {
+    use rustc_middle::ty::layout::{LayoutCx, LayoutOf};
+    use rustc_middle::ty::{ParamEnv, Ty, TyCtxt};
+
     use super::*;
     use crate::layout::tree::rustc::Err;
 
-    use rustc_middle::ty::layout::LayoutCx;
-    use rustc_middle::ty::layout::LayoutOf;
-    use rustc_middle::ty::ParamEnv;
-    use rustc_middle::ty::Ty;
-    use rustc_middle::ty::TyCtxt;
-
     impl<'tcx> MaybeTransmutableQuery<Ty<'tcx>, TyCtxt<'tcx>> {
         /// This method begins by converting `src` and `dst` from `Ty`s to `Tree`s,
         /// then computes an answer using those trees.

compiler/rustc_transmute/src/maybe_transmutable/query_context.rs

@@ -34,9 +34,10 @@ pub(crate) mod test {
 
 #[cfg(feature = "rustc")]
 mod rustc {
-    use super::*;
     use rustc_middle::ty::{Ty, TyCtxt};
 
+    use super::*;
+
     impl<'tcx> super::QueryContext for TyCtxt<'tcx> {
         type Def = layout::rustc::Def<'tcx>;
         type Ref = layout::rustc::Ref<'tcx>;

compiler/rustc_transmute/src/maybe_transmutable/tests.rs

@@ -1,12 +1,12 @@
+use itertools::Itertools;
+
 use super::query_context::test::{Def, UltraMinimal};
 use crate::maybe_transmutable::MaybeTransmutableQuery;
 use crate::{layout, Reason};
-use itertools::Itertools;
 
 mod safety {
-    use crate::Answer;
-
     use super::*;
+    use crate::Answer;
 
     type Tree = layout::Tree<Def, !>;
 
@@ -63,9 +63,8 @@ mod safety {
 }
 
 mod bool {
-    use crate::Answer;
-
     use super::*;
+    use crate::Answer;
 
     #[test]
     fn should_permit_identity_transmutation_tree() {