macports.tcl: Add missing braces around expressions.
macports.tcl: Add missing braces around expressions.

See https://lists.macosforge.org/pipermail/macports-dev/2013-June/022951.html
and https://lists.macosforge.org/pipermail/macports-dev/2013-June/022970.html.

git-svn-id: 620571fa9b4bd0cbce9a0cf901e91ef896adbf27@106981 d073be05-634f-4543-b044-5fe20cf6d1d6

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