Issue #498: Fix a memory leak bug introduced in test_double_serializer in 485f2a02 by adding a json_object_put call.

tests/test_double_serializer.c

@@ -78,5 +78,6 @@ int main()
 
 	obj = json_object_new_double(-12.0);
 	printf("obj(-12.0).to_string(default format)=%s\n", json_object_to_json_string(obj));
+	json_object_put(obj);
 
 }