added new arithmetic optimization flags added (a - x) + x optimization removed #if 0 code used is_Bad()
added new arithmetic optimization flags
added (a - x) + x optimization
removed #if 0 code
used is_Bad()

[r6102]

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