Replace `rustc_data_structures::thin_vec::ThinVec` with `thin_vec::ThinVec`.

`rustc_data_structures::thin_vec::ThinVec` looks like this:
```
pub struct ThinVec<T>(Option<Box<Vec<T>>>);
```
It's just a zero word if the vector is empty, but requires two
allocations if it is non-empty. So it's only usable in cases where the
vector is empty most of the time.

This commit removes it in favour of `thin_vec::ThinVec`, which is also
word-sized, but stores the length and capacity in the same allocation as
the elements. It's good in a wider variety of situation, e.g. in enum
variants where the vector is usually/always non-empty.

The commit also:
- Sorts some `Cargo.toml` dependency lists, to make additions easier.
- Sorts some `use` item lists, to make additions easier.
- Changes `clean_trait_ref_with_bindings` to take a
  `ThinVec<TypeBinding>` rather than a `&[TypeBinding]`, because this
  avoid some unnecessary allocations.

1 files changed, 4 insertions, 6 deletions

diff --git a/compiler/rustc_query_impl/src/plumbing.rs b/compiler/rustc_query_impl/src/plumbing.rs
index eab627c5d4c..f38f29e14af 100644
--- a/compiler/rustc_query_impl/src/plumbing.rs
+++ b/compiler/rustc_query_impl/src/plumbing.rs
@@ -4,6 +4,9 @@
 
 use crate::keys::Key;
 use crate::{on_disk_cache, Queries};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_data_structures::sync::Lock;
+use rustc_errors::{Diagnostic, Handler};
 use rustc_middle::dep_graph::{self, DepKind, DepNodeIndex, SerializedDepNodeIndex};
 use rustc_middle::ty::tls::{self, ImplicitCtxt};
 use rustc_middle::ty::{self, TyCtxt};
@@ -12,14 +15,9 @@ use rustc_query_system::ich::StableHashingContext;
 use rustc_query_system::query::{
     QueryContext, QueryJobId, QueryMap, QuerySideEffects, QueryStackFrame,
 };
-
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_data_structures::sync::Lock;
-use rustc_data_structures::thin_vec::ThinVec;
-use rustc_errors::{Diagnostic, Handler};
-
 use std::any::Any;
 use std::num::NonZeroU64;
+use thin_vec::ThinVec;
 
 #[derive(Copy, Clone)]
 pub struct QueryCtxt<'tcx> {