get_screen_size

static VALUE
readline_s_get_screen_size(VALUE self)
{
    int rows, columns;
    VALUE res;

    rl_get_screen_size(&rows, &columns);
    res = rb_ary_new();
    rb_ary_push(res, INT2NUM(rows));
    rb_ary_push(res, INT2NUM(columns));
    return res;
}