Fix btor concat
Fix btor concat

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