Time#gmtoff

VALUE
rb_time_utc_offset(VALUE time)
{
    struct time_object *tobj;

    GetTimeval(time, tobj);

    if (TZMODE_UTC_P(tobj)) {
        return INT2FIX(0);
    }
    else {
        MAKE_TM(time, tobj);
        return tobj->vtm.utc_offset;
    }
}