benewalloc: refactorign assignment_t struct is not needed anymore we can save ir_node* directly
benewalloc: refactorign assignment_t struct is not needed anymore we can save ir_node* directly

[r26423]

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