rev-upgrade: Break circular dependencies in dependency resolution by selecting port with the least dependents
rev-upgrade: Break circular dependencies in dependency resolution by selecting port with the least dependents

Although it shouldn't happen, I've had problems with circular dependencies when
determining the rebuild-order of ports in rev-upgrade. To prevent such a cycle
triggering an endless loop, this code is introduced.

git-svn-id: 620571fa9b4bd0cbce9a0cf901e91ef896adbf27@89661 d073be05-634f-4543-b044-5fe20cf6d1d6

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