Medium: Squid: fix getting PIDs of squid processes (lf#2653)

Squid uses netstat -apn to figure out the list of processes
serving clients, but didn't take into account the connections in
the TIME_WAIT state which have no process. This could result in
failed stop (probably other false positives too).

Thanks to bugsquid@fantasymail.de for finding the problem and
suggesting a fix.