MEDIUM: sessions: Use the new _HA_ATOMIC_* macros.

Use the new _HA_ATOMIC_* macros and add barriers where needed.
diff --git a/src/session.c b/src/session.c
index 58317b8..ab49fb6 100644
--- a/src/session.c
+++ b/src/session.c
@@ -55,8 +55,8 @@
 		vars_init(&sess->vars, SCOPE_SESS);
 		sess->task = NULL;
 		sess->t_handshake = -1; /* handshake not done yet */
-		HA_ATOMIC_ADD(&totalconn, 1);
-		HA_ATOMIC_ADD(&jobs, 1);
+		_HA_ATOMIC_ADD(&totalconn, 1);
+		_HA_ATOMIC_ADD(&jobs, 1);
 		LIST_INIT(&sess->srv_list);
 		sess->idle_conns = 0;
 	}
@@ -97,7 +97,7 @@
 		pool_free(pool_head_sess_srv_list, srv_list);
 	}
 	pool_free(pool_head_session, sess);
-	HA_ATOMIC_SUB(&jobs, 1);
+	_HA_ATOMIC_SUB(&jobs, 1);
 }
 
 /* callback used from the connection/mux layer to notify that a connection is