Make keep nodes in return blocks dead if there are any
Make keep nodes in return blocks dead if there are any

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