portlint.tcl: when "port lint" prints the error "Line X has unrecognized PortGroup", prevent subsequent error message "can't read 'portgroup': no such variable"; see https://lists.macosforge.org/pipermail/macports-dev/2012-December/021207.html
portlint.tcl: when "port lint" prints the error "Line X has unrecognized PortGroup", prevent subsequent error message "can't read 'portgroup': no such variable"; see https://lists.macosforge.org/pipermail/macports-dev/2012-December/021207.html

git-svn-id: 620571fa9b4bd0cbce9a0cf901e91ef896adbf27@102570 d073be05-634f-4543-b044-5fe20cf6d1d6

macports/macports-base,neverpanic/macports-base,danchr/macports-base,danchr/macports-base,neverpanic/macports-base,macports/macports-base