Added mul to mux conversion to "opt_const -fine"
Added mul to mux conversion to "opt_const -fine"

antmicro/yosys,SymbiFlow/yosys,cliffordwolf/yosys,SymbiFlow/yosys,SymbiFlow/yosys,SymbiFlow/yosys,YosysHQ/yosys,YosysHQ/yosys,azonenberg/yosys,azonenberg/yosys,antmicro/yosys,cliffordwolf/yosys,azonenberg/yosys,swallat/yosys,YosysHQ/yosys,azonenberg/yosys,swallat/yosys,cliffordwolf/yosys,swallat/yosys,azonenberg/yosys,cliffordwolf/yosys,azonenberg/yosys,cliffordwolf/yosys,antmicro/yosys,swallat/yosys,azonenberg/yosys,antmicro/yosys,cliffordwolf/yosys,azonenberg/yosys,SymbiFlow/yosys,cliffordwolf/yosys,swallat/yosys,cliffordwolf/yosys,swallat/yosys,YosysHQ/yosys,swallat/yosys,antmicro/yosys,swallat/yosys,antmicro/yosys,azonenberg/yosys,SymbiFlow/yosys,YosysHQ/yosys,swallat/yosys,YosysHQ/yosys,YosysHQ/yosys,YosysHQ/yosys,SymbiFlow/yosys,antmicro/yosys,antmicro/yosys,cliffordwolf/yosys,SymbiFlow/yosys