[map] Add a couple more sink interfaces

src/hb-map.hh

@@ -320,6 +320,10 @@ struct hb_hashmap_t
   { set (v.first, v.second); return *this; }
   hb_hashmap_t& operator << (const hb_pair_t<K, V&&>& v)
   { set (v.first, std::move (v.second)); return *this; }
+  hb_hashmap_t& operator << (const hb_pair_t<K&&, V>& v)
+  { set (std::move (v.first), v.second); return *this; }
+  hb_hashmap_t& operator << (const hb_pair_t<K&&, V&&>& v)
+  { set (std::move (v.first), std::move (v.second)); return *this; }
 
   protected:
 

src/test-map.cc

@@ -199,6 +199,8 @@ main (int argc, char **argv)
     assert (v.length == 1);
     m1 << hb_pair_t<vector_t, vector_t&&> {vector_t {4}, std::move (v)};
     assert (v.length == 0);
+    m1 << hb_pair_t<vector_t&&, vector_t> {vector_t {4}, vector_t {5}};
+    m1 << hb_pair_t<vector_t&&, vector_t&&> {vector_t {4}, vector_t {5}};
 
     hb_hashmap_t<vector_t, vector_t> m2;
     vector_t v2 {3};