- Do not remove keep-alives during optimize_graph_df(), kill only Bads and doublets
- Do not remove keep-alives during optimize_graph_df(), kill only Bads and doublets

[r24571]

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