objlist: Add support for statically allocated lists.

Similar to similar support for lists.
diff --git a/py/objlist.h b/py/objlist.h
new file mode 100644
index 0000000..cc8d7de
--- /dev/null
+++ b/py/objlist.h
@@ -0,0 +1,6 @@
+typedef struct _mp_obj_list_t {
+    mp_obj_base_t base;
+    machine_uint_t alloc;
+    machine_uint_t len;
+    mp_obj_t *items;
+} mp_obj_list_t;