fix formatting

Author: calvinhirsch

compiler/rustc_type_ir/src/search_graph/mod.rs

@@ -13,7 +13,7 @@
 //! behavior as long as the resulting behavior is still correct.
 use std::cmp::Ordering;
 use std::collections::hash_map::Entry;
-use std::collections::{btree_map, BTreeMap};
+use std::collections::{BTreeMap, btree_map};
 use std::fmt::Debug;
 use std::hash::Hash;
 use std::iter;