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/markdown/tests/parse.rs

@@ -1,6 +1,7 @@
-use super::*;
 use ParseOpt as PO;
 
+use super::*;
+
 #[test]
 fn test_parse_simple() {
     let buf = "**abcd** rest";

compiler/rustc_errors/src/markdown/tests/term.rs

@@ -1,5 +1,6 @@
 use std::io::BufWriter;
 use std::path::PathBuf;
+
 use termcolor::{BufferWriter, ColorChoice};
 
 use super::*;