MEDIUM: various: Use __ha_barrier_atomic* when relevant.

When protecting data modified by atomic operations, use __ha_barrier_atomic*
to avoid unneeded barriers on x86.
diff --git a/src/fd.c b/src/fd.c
index 581c5aa..cb9df1f 100644
--- a/src/fd.c
+++ b/src/fd.c
@@ -203,7 +203,7 @@
 		goto done;
 	if (!HA_ATOMIC_CAS(&_GET_NEXT(fd, off), &next, -2))
 		goto redo_next;
-	__ha_barrier_store();
+	__ha_barrier_atomic_store();
 
 	new = fd;
 redo_last:
@@ -292,7 +292,7 @@
 	if (unlikely(!HA_ATOMIC_CAS(&_GET_PREV(fd, off), &prev, -2)))
 		goto lock_self_prev;
 #endif
-	__ha_barrier_store();
+	__ha_barrier_atomic_store();
 
 	/* Now, lock the entries of our neighbours */
 	if (likely(prev != -1)) {