[iter] Fix hb_sink() to accept rvalue
diff --git a/src/test-iter.cc b/src/test-iter.cc
index 17a1972..fe3c8f3 100644
--- a/src/test-iter.cc
+++ b/src/test-iter.cc
@@ -186,6 +186,10 @@
   ;
 
   + hb_iter (src)
+  | hb_sink (hb_array (dst))
+  ;
+
+  + hb_iter (src)
   | hb_apply (&st)
   ;