rewrite compiler selection process: now allows to override any configure-related variable in the Portfile even if a compiler collection was chosen
rewrite compiler selection process: now allows to override any configure-related variable in the Portfile even if a compiler collection was chosen

git-svn-id: 620571fa9b4bd0cbce9a0cf901e91ef896adbf27@28474 d073be05-634f-4543-b044-5fe20cf6d1d6

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