Robustify ${prefix}/man creation. Only try to create the symlink if there's nothing there already. If there is a symlink there already, replace it (in case it was stale)
Robustify ${prefix}/man creation. Only try to create the symlink
if there's nothing there already. If there is a symlink there already,
replace it (in case it was stale)

git-svn-id: 620571fa9b4bd0cbce9a0cf901e91ef896adbf27@5705 d073be05-634f-4543-b044-5fe20cf6d1d6

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