Fix tidy 2

Author: Sa4dUs

compiler/rustc_span/src/symbol.rs

@@ -542,6 +542,7 @@ symbols! {
         audit_that,
         augmented_assignments,
         auto_traits,
+        autodiff,
         autodiff_forward,
         autodiff_reverse,
         automatically_derived,
@@ -917,7 +918,6 @@ symbols! {
         enumerate_method,
         env,
         env_CFG_RELEASE: env!("CFG_RELEASE"),
-        autodiff,
         eprint_macro,
         eprintln_macro,
         eq,