tests: add ecp5 latch testcase with -abc9
tests: add ecp5 latch testcase with -abc9

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