Author: Henrik Nordstrom <hno@squid-cache.org>

Author: Henrik Nordstrom <hno@squid-cache.org>
Support RFC 5861 Cache-Control: stale-if-error option

The default behaviour for Squid is to present the stale object when
revalidation fails with a 5xx error.

stale-if-error places a maximum limit on how long this stale object may
be sent. After the limit has passed Squid is required to present the 5xx
message to the client.

Original code for Squid-2 was sponsored by Yahoo!.

Portage done by Alex Rousskov and Amos Jeffries.