- speed-up: if a partition has NO follower we can use the old split algorithm
- speed-up: if a partition has NO follower we can use the old split algorithm

[r21039]

davidgiven/libfirm,libfirm/libfirm,killbug2004/libfirm,libfirm/libfirm,8l/libfirm,libfirm/libfirm,8l/libfirm,8l/libfirm,jonashaag/libfirm,MatzeB/libfirm,killbug2004/libfirm,killbug2004/libfirm,davidgiven/libfirm,killbug2004/libfirm,MatzeB/libfirm,killbug2004/libfirm,8l/libfirm,libfirm/libfirm,MatzeB/libfirm,davidgiven/libfirm,davidgiven/libfirm,davidgiven/libfirm,MatzeB/libfirm,jonashaag/libfirm,8l/libfirm,killbug2004/libfirm,jonashaag/libfirm,jonashaag/libfirm,MatzeB/libfirm,MatzeB/libfirm,8l/libfirm,libfirm/libfirm,8l/libfirm,davidgiven/libfirm,davidgiven/libfirm,jonashaag/libfirm,MatzeB/libfirm,killbug2004/libfirm,jonashaag/libfirm,jonashaag/libfirm