squid: security bump to version 4.4

Fixes SQUID-2018_4:

Due to incorrect input handling, Squid is vulnerable to a Cross-Site
Scripting vulnerability when generating HTTPS response messages about TLS
errors.

For more details, see the advisory:

http://www.squid-cache.org/Advisories/SQUID-2018_4.txt



Signed-off-by: Peter Korsgaard <peter@korsgaard.com>