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_index/src/interval.rs

@@ -1,7 +1,6 @@
 use std::iter::Step;
 use std::marker::PhantomData;
-use std::ops::RangeBounds;
-use std::ops::{Bound, Range};
+use std::ops::{Bound, Range, RangeBounds};
 
 use smallvec::SmallVec;