Add an info string symbol for bad states in btor backend
Add an info string symbol for bad states in btor backend

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