Update the port to squid-2.5.stable1.

Notable features:

• I'm building _all_ of the error page languages now
• I'm building a handful of the helper modules (the ones that don't require ldap or samba to be installed)
• underscores in hostnames are enabled - every few weeks we squid people get emails asking why someone can't get to some_user.geocities.com . Bad geocities. :)