We do not need to place Phis in dead blocks.
We do not need to place Phis in dead blocks.

This fixes opt/jumpthreading3.c.

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