5045 use atomic_{inc,dec}_* instead of atomic_add_*

@@ -119,20 +119,20 @@
  * Put a hold on a label structure.
  */
 void
 label_hold(ts_label_t *lab)
 {
-        atomic_add_32(&lab->tsl_ref, 1);
+        atomic_inc_32(&lab->tsl_ref);
 }
 
 /*
  * Release previous hold on a label structure.  Free it if refcnt == 0.
  */
 void
 label_rele(ts_label_t *lab)
 {
-        if (atomic_add_32_nv(&lab->tsl_ref, -1) == 0)
+        if (atomic_dec_32_nv(&lab->tsl_ref) == 0)
                 kmem_cache_free(tslabel_cache, lab);
 }
 
 bslabel_t *
 label2bslabel(ts_label_t *lab)