abc9 to use mergeability class to differentiate sync/async
abc9 to use mergeability class to differentiate sync/async

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