Change orderings of Debug for the Atomic types to Relaxed.

This reduces synchronization between threads when
debugging the atomic types.
Reducing the synchronization means that executions with and
without the debug calls will be more consistent,
making it easier to debug.

library/core/src/sync/atomic.rs

@@ -1517,7 +1517,7 @@ macro_rules! atomic_int {
         #[$stable_debug]
         impl fmt::Debug for $atomic_type {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-                fmt::Debug::fmt(&self.load(Ordering::SeqCst), f)
+                fmt::Debug::fmt(&self.load(Ordering::Relaxed), f)
             }
         }
 
@@ -2996,15 +2996,15 @@ pub fn compiler_fence(order: Ordering) {
 #[stable(feature = "atomic_debug", since = "1.3.0")]
 impl fmt::Debug for AtomicBool {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Debug::fmt(&self.load(Ordering::SeqCst), f)
+        fmt::Debug::fmt(&self.load(Ordering::Relaxed), f)
     }
 }
 
 #[cfg(target_has_atomic_load_store = "ptr")]
 #[stable(feature = "atomic_debug", since = "1.3.0")]
 impl<T> fmt::Debug for AtomicPtr<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Debug::fmt(&self.load(Ordering::SeqCst), f)
+        fmt::Debug::fmt(&self.load(Ordering::Relaxed), f)
     }
 }