Add initial USE_SIMD=FOUR12 support
Add initial USE_SIMD=FOUR12 support

YosysHQ/yosys,antmicro/yosys,SymbiFlow/yosys,cliffordwolf/yosys,cliffordwolf/yosys,SymbiFlow/yosys,YosysHQ/yosys,cliffordwolf/yosys,antmicro/yosys,cliffordwolf/yosys,SymbiFlow/yosys,cliffordwolf/yosys,YosysHQ/yosys,antmicro/yosys,YosysHQ/yosys,YosysHQ/yosys,cliffordwolf/yosys,antmicro/yosys,antmicro/yosys,antmicro/yosys,SymbiFlow/yosys,antmicro/yosys,antmicro/yosys,cliffordwolf/yosys,SymbiFlow/yosys,SymbiFlow/yosys,cliffordwolf/yosys,cliffordwolf/yosys,SymbiFlow/yosys,SymbiFlow/yosys,YosysHQ/yosys,YosysHQ/yosys,YosysHQ/yosys