verify that the predecessor of a block is a cfop
verify that the predecessor of a block is a cfop

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