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_errors/src/snippet.rs

@@ -1,8 +1,9 @@
 // Code for annotating snippets.
 
-use crate::{Level, Loc};
 use rustc_macros::{Decodable, Encodable};
 
+use crate::{Level, Loc};
+
 #[derive(Clone, Debug, PartialOrd, Ord, PartialEq, Eq)]
 pub struct Line {
     pub line_index: usize,