yosys-netlist-json: Make creator optional
yosys-netlist-json: Make creator optional

rqou/openfpga,azonenberg/openfpga,azonenberg/openfpga,rqou/openfpga,azonenberg/openfpga,rqou/openfpga,azonenberg/openfpga,azonenberg/openfpga,rqou/openfpga,rqou/openfpga