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_hir_analysis/src/variance/constraints.rs

@@ -6,8 +6,7 @@
 use hir::def_id::{DefId, LocalDefId};
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
-use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_middle::ty::{GenericArgKind, GenericArgsRef};
+use rustc_middle::ty::{self, GenericArgKind, GenericArgsRef, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
 
 use super::terms::VarianceTerm::*;