Fixed bug in conv-conv optimization: We have to assure, that we don't change the mode when deleting the conv.
Fixed bug in conv-conv optimization: We have to assure, that we don't change the mode when deleting the conv.

[r23009]

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