Login time-out is broken

Perhaps this is a clearer way to describe the problem.
The Bakery cookie is set in two places

993:  setcookie('CHOCOLATECHIP', bakery_mix(serialize($cookie), 1), $_SERVER['REQUEST_TIME'] + variable_get('bakery_freshness', '3600'), '/', variable_get('bakery_domain', ''));</
1038: setcookie('OATMEAL', bakery_mix(serialize($cookie), 1), $_SERVER['REQUEST_TIME'] + variable_get('bakery_freshness', '3600'), '/', variable_get('bakery_domain', ''));

If both cases you'll notice that the third parameter is $_SERVER['REQUEST_TIME'] + variable_get('bakery_freshness', '3600').

However, the code that verifies the cookie is stil valid looks like this.

968: if ($signature == $cookie['signature'] && $cookie['timestamp'] + variable_get('bakery_freshness', '3600') >= $_SERVER['REQUEST_TIME']) {

Due to the joys of working with cookies this means that every Bakery cookie effectivly has 2 expiration dates.

1. When $cookie['timestamp'] + variable_get('bakery_freshness', '3600') >= $_SERVER['REQUEST_TIME']
2. When the expiration date set on the cookie is in the past according to the client computer.

That second option is the one that is causing me trouble. As far as I can tell there are two ways to solve this problem.

1. Use some javascript to collect the current time on the client's computer, and use that timestamp for setting the cookie expiration.
2. Set the expiration date really far in the future and take advantage of the fact that the first method of expiration will properly expire it.

Patch changes cookie expiration on client computer to 10 years beyond default expiration. That should resolve all but the most extreme of incorrect client clock problems.

For some reason I don't quite understand my copy of Git will only create multiple patches for me. I'm probably doing something wrong. Hope that is not to much of a problem.

First patch is unchanged from above. Second patch adds comments requested by greggles.

Forgot to mark it as needs review. Sorry.