Added local optimizations.
Added local optimizations.

- Mux((a & 1) != 0, 0, b) => -a & b
- Mux((a & 1) == 0, 0, b) => (a - 1) & b

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