Add warning if synth_xilinx -abc9 with family != xc7
Add warning if synth_xilinx -abc9 with family != xc7

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