lower_dw must deactivate edges
lower_dw must deactivate edges

There might be some ProjL nodes reachable via out edges
and the following "local" phase does enqueue_users for
optimized nodes, which might visit the 'undead' ProjL.

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