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/registry.rs

@@ -1,6 +1,7 @@
-use crate::ErrCode;
 use rustc_data_structures::fx::FxHashMap;
 
+use crate::ErrCode;
+
 #[derive(Debug)]
 pub struct InvalidErrorCode;