Revert "[map] Allow std::move-ing keys into the map"

This reverts commit f657ef7e57.

This breaks many compilers with messages like this:

hb-subset-plan.hh:226: undefined reference to `OT::head::tableTag'

I'm out of my depth re how to fix it.

src/hb-map.hh

@@ -186,7 +186,7 @@ struct hb_hashmap_t
     {
       if (old_items[i].is_real ())
       {
-	set_with_hash (std::move (old_items[i].key),
+	set_with_hash (old_items[i].key,
 		       old_items[i].hash,
 		       std::move (old_items[i].value));
       }
@@ -199,9 +199,7 @@ struct hb_hashmap_t
   }
 
   template <typename VV>
-  bool set (const K &key, VV&& value) { return set_with_hash (hb_ridentity (key), hb_hash (key), std::forward<VV> (value)); }
+  bool set (K key, VV&& value) { return set_with_hash (key, hb_hash (key), std::forward<VV> (value)); }
-  template <typename VV>
-  bool set (K&& key, VV&& value) { return set_with_hash (std::move (key), hb_hash (key), std::forward<VV> (value)); }
 
   const V& get (K key) const
   {
@@ -210,8 +208,7 @@ struct hb_hashmap_t
     return item.is_real () && item == key ? item.value : item_t::default_value ();
   }
 
-  void del (const K &key) { set_with_hash (hb_ridentity (key), hb_hash (key), item_t::default_value (), true); }
+  void del (K key) { set_with_hash (key, hb_hash (key), item_t::default_value (), true); }
-  void del (K&& key) { set_with_hash (std::move (key), hb_hash (key), item_t::default_value (), true); }
 
   /* Has interface. */
   typedef const V& value_t;
@@ -327,8 +324,8 @@ struct hb_hashmap_t
 
   protected:
 
-  template <typename KK, typename VV>
+  template <typename VV>
-  bool set_with_hash (KK&& key, uint32_t hash, VV&& value, bool is_delete=false)
+  bool set_with_hash (K key, uint32_t hash, VV&& value, bool is_delete=false)
   {
     if (unlikely (!successful)) return false;
     if (unlikely ((occupancy + occupancy / 2) >= mask && !resize ())) return false;
@@ -344,7 +341,7 @@ struct hb_hashmap_t
 	population--;
     }
 
-    item.key = std::forward<KK> (key);
+    item.key = key;
     item.value = std::forward<VV> (value);
     item.hash = hash;
     item.set_used (true);

src/test-map.cc

@@ -228,8 +228,10 @@ main (int argc, char **argv)
   {
     hb_hashmap_t<hb::unique_ptr<hb_set_t>, hb::unique_ptr<hb_set_t>> m;
 
-    m.set (hb::unique_ptr<hb_set_t> (hb_set_get_empty ()),
+    // Doesn't work.
-	   hb::unique_ptr<hb_set_t> (hb_set_get_empty ()));
+    // See commit f657ef7e57c889309c2d9d37934368ca255f9d5b and its revert.
+    //m.set (hb::unique_ptr<hb_set_t> (hb_set_get_empty ()),
+    //       hb::unique_ptr<hb_set_t> (hb_set_get_empty ()));
     m.get (hb::unique_ptr<hb_set_t> (hb_set_get_empty ()));
     m.iter_ref ();
     m.keys_ref ();