avoid some of the mode_b lowering related out-edge warnings
avoid some of the mode_b lowering related out-edge warnings

[r16142]

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