Use SeqCst at places

... TODO: Describe rationale ...
... TODO: Is that all that's needed? ...

Maybe a solution for #76.

src/debt/list.rs

@@ -85,7 +85,7 @@ impl Node {
         //
         // Note that the other pointers in the chain never change and are *ordinary* pointers. The
         // whole linked list is synchronized through the head.
-        let mut current = unsafe { LIST_HEAD.load(Acquire).as_ref() };
+        let mut current = unsafe { LIST_HEAD.load(SeqCst).as_ref() };
         while let Some(node) = current {
             let result = f(node);
             if result.is_some() {
@@ -143,7 +143,7 @@ impl Node {
                 .in_use
                 // We claim a unique control over the generation and the right to write to slots if
                 // they are NO_DEPT
-                .compare_exchange(NODE_UNUSED, NODE_USED, Acquire, Relaxed)
+                .compare_exchange(NODE_UNUSED, NODE_USED, SeqCst, Relaxed)
                 .is_ok()
             {
                 Some(node)
@@ -167,7 +167,7 @@ impl Node {
                     head, node,
                     // We need to release *the whole chain* here. For that, we need to
                     // acquire it first.
-                    AcqRel, Relaxed, // Nothing changed, go next round of the loop.
+                    SeqCst, Relaxed, // Nothing changed, go next round of the loop.
                 ) {
                     head = old;
                 } else {

src/strategy/hybrid.rs

@@ -68,7 +68,7 @@ impl<T: RefCnt> HybridProtection<T> {
         // We already synchronized the start of the sequence by SeqCst in the new_helping vs swap on
         // the pointer. We just need to make sure to bring the pointee in (this can be newer than
         // what we got in the Debt)
-        let candidate = storage.load(Acquire);
+        let candidate = storage.load(SeqCst);
 
         // Try to replace the debt with our candidate. If it works, we get the debt slot to use. If
         // not, we get a replacement value, already protected and a debt to take care of.