Create Conv instead of Bitcast for the same arithmetic.
Create Conv instead of Bitcast for the same arithmetic.

This fixes opt/fehler310.c.

MatzeB/libfirm,MatzeB/libfirm,MatzeB/libfirm,MatzeB/libfirm,MatzeB/libfirm,libfirm/libfirm,libfirm/libfirm,MatzeB/libfirm,MatzeB/libfirm,jonashaag/libfirm,jonashaag/libfirm,jonashaag/libfirm,libfirm/libfirm,jonashaag/libfirm,jonashaag/libfirm,libfirm/libfirm,jonashaag/libfirm,libfirm/libfirm,jonashaag/libfirm