Fix transformation, when the load mem proj of a dest AM pattern has multiple users.
Fix transformation, when the load mem proj of a dest AM pattern has multiple users.

[r20272]

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