www/squid: Heimdal option build fixes

• Fix squid build with Heimdal from ports.
• Additionally fix squid build with base Heimdal when Heimdal from ports is installed.

PR: 205461
Reported by: dewayne@heuristicsystems.com.au
Submitted by: Pavel Timofeev <timp87@gmail.com> (maintainer)
MFH: 2016Q1 (build fix blanket)