Add info to external pointer free callback. (#4642)

Furthermore reduce memory consumption when only
one external pointer is assigned to an object.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

tests/unit-core/test-native-pointer.c

@@ -22,9 +22,11 @@ static void *global_p = (void *) &global_int;
 static int global_counter = 0;
 
 static void
-native_free_callback (void *native_p) /**< native pointer */
+native_free_callback (void *native_p, /**< native pointer */
+                      jerry_object_native_info_t *info_p) /**< native info */
 {
   (void) native_p;
+  TEST_ASSERT (info_p->free_cb == native_free_callback);
   global_counter++;
 } /* native_free_callback */