Prevent compare simplification for trivial compares.
Prevent compare simplification for trivial compares.

The optimization does not work properly for relation_true and relation_false.

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