add more builtin cells

src/builtin_cells.rs

@@ -53,6 +53,8 @@ fn make_binop_callable(name: &str, celltype: &'static str) -> Callable {
 pub fn get_builtins() -> Vec<Callable> {
     vec![
         make_binop_callable("and", "$and"),
+        make_binop_callable("or", "$or"),
         make_binop_callable("xor", "$xor"),
+        make_binop_callable("xnor", "$xnor"),
     ]
 }