I don't know why, and anyone who wants to fix this or give me clues would make me happy. For now, my personal box is using gcc 3.3 instead (sudo gcc_select 3.3), because I have no desire to try to deal with the problem.
Of course, if using the Mac::Carbon that is already included in Tiger, you don't need to care, because it has already been built. Presumably with gcc 3.3.
The scripts needed to do so are included too.
./gluemac '/System/Library/CoreServices/System Events.app'