A few small cleanups for newtype_index

Remove the `..` from the body, only a few invocations used it and it's
inconsistent with rust syntax.

Use `;` instead of `,` between consts. As the Rust syntax gods inteded.

compiler/rustc_borrowck/src/constraints/mod.rs

@@ -116,12 +116,10 @@ impl<'tcx> fmt::Debug for OutlivesConstraint<'tcx> {
 
 rustc_index::newtype_index! {
     #[debug_format = "OutlivesConstraintIndex({})"]
-    pub struct OutlivesConstraintIndex {
-    }
+    pub struct OutlivesConstraintIndex {}
 }
 
 rustc_index::newtype_index! {
     #[debug_format = "ConstraintSccIndex({})"]
-    pub struct ConstraintSccIndex {
-    }
+    pub struct ConstraintSccIndex {}
 }

compiler/rustc_borrowck/src/dataflow.rs

@@ -109,8 +109,7 @@ impl_visitable! {
 
 rustc_index::newtype_index! {
     #[debug_format = "bw{}"]
-    pub struct BorrowIndex {
-    }
+    pub struct BorrowIndex {}
 }
 
 /// `Borrows` stores the data used in the analyses that track the flow

compiler/rustc_borrowck/src/location.rs

@@ -21,8 +21,7 @@ pub struct LocationTable {
 
 rustc_index::newtype_index! {
     #[debug_format = "LocationIndex({})"]
-    pub struct LocationIndex {
-    }
+    pub struct LocationIndex {}
 }
 
 #[derive(Copy, Clone, Debug)]

compiler/rustc_borrowck/src/member_constraints.rs

@@ -56,8 +56,7 @@ pub(crate) struct NllMemberConstraint<'tcx> {
 
 rustc_index::newtype_index! {
     #[debug_format = "MemberConstraintIndex({})"]
-    pub(crate) struct NllMemberConstraintIndex {
-    }
+    pub(crate) struct NllMemberConstraintIndex {}
 }
 
 impl Default for MemberConstraintSet<'_, ty::RegionVid> {

compiler/rustc_borrowck/src/type_check/liveness/local_use_map.rs

@@ -46,7 +46,7 @@ struct Appearance {
 }
 
 rustc_index::newtype_index! {
-    pub struct AppearanceIndex { .. }
+    pub struct AppearanceIndex {}
 }
 
 impl vll::LinkElem for Appearance {