py: Allow registration of modules at their definition.

During make, makemoduledefs.py parses the current builds c files for
MP_REGISTER_MODULE(module_name, obj_module, enabled_define)

These are used to generate a header with the required entries for
"mp_rom_map_elem_t mp_builtin_module_table[]" in py/objmodule.c

py/modarray.c

@@ -40,4 +40,6 @@ const mp_obj_module_t mp_module_array = {
     .globals = (mp_obj_dict_t*)&mp_module_array_globals,
 };
 
+MP_REGISTER_MODULE(MP_QSTR_array, mp_module_array, MICROPY_PY_ARRAY);
+
 #endif