change random number generator success ordering to AcqRel

src/backoff.rs

@@ -63,7 +63,7 @@ pub fn random() -> usize {
  current,
  // Linear congruential generator
  current.wrapping_mul(1103515245).wrapping_add(12345),
- Ordering::Release,
+ Ordering::AcqRel,
  Ordering::Acquire,
  ) {
  // Successfully updated current value to next random number, so current value is owned by this thread and valid to use