Log Message:
Update squid package to 2.6.18 (2.6.STABLE18)

Changes to squid-2.6.STABLE18 (10 Jan 2008)

	- Fix 2 assertion failures related to the fix for SQUID-2007:2
	- GPL license cleanup to GPLv2 or later. One file in edir_digest_auth
	  was GPLv2 only, now replaced with a GPLv2 or later licensed vesion.
	- Minor cleanups to make certain 64-bit platforms happier
	- Several Digest authentication bugs fixed wich was causing random
	  authenitcation popups or failures.
	- --with-valgrind-debug updated for valgrind-3.3.0.