Added some missing cases to ir_is_optimizable_mux.
Added some missing cases to ir_is_optimizable_mux.

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