tweak optimistic split heuristic to take execfreq of the potential copy into account
tweak optimistic split heuristic to take execfreq of the potential copy into account

[r26483]

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