remove unnecessary underscores in stable_mir::mir::visit.rs

Author: makai410

compiler/stable_mir/src/mir/visit.rs

@@ -436,8 +436,6 @@ macro_rules! super_body {
 macro_rules! visit_place_fns {
     (mut) => {
         fn super_place(&mut self, place: &mut Place, ptx: PlaceContext, location: Location) {
-            let _ = location;
-            let _ = ptx;
             self.visit_local(&mut place.local, ptx, location);
 
             for elem in place.projection.iter_mut() {
@@ -478,8 +476,6 @@ macro_rules! visit_place_fns {
 
     () => {
         fn super_place(&mut self, place: &Place, ptx: PlaceContext, location: Location) {
-            let _ = location;
-            let _ = ptx;
             self.visit_local(&place.local, ptx, location);
 
             for (idx, elem) in place.projection.iter().enumerate() {