Workaround broken GCC va_args on arm64-darwin

mp_printf is called with uint16_t which is then accessed with va_args as 8-byte
size_t. My understanding of C is that this is legal but with GCC the returned
value is corrupted.

Author: mmilata

py/obj.c

@@ -119,7 +119,7 @@ void mp_obj_print_helper(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t
     if (type->print != NULL) {
         type->print((mp_print_t *)print, o_in, kind);
     } else {
-        mp_printf(print, "<%q>", type->name);
+        mp_printf(print, "<%q>", (qstr)type->name);
     }
 }