[WIP] Add nextpnr-xilinx-already-synth toolchain#504

mkurc-ant wants to merge 3 commits intochipsalliance:mainchipsalliance/fpga-tool-perf:mainfrom

antmicro:nextpnr-xilinx-already-synthantmicro/fpga-tool-perf:nextpnr-xilinx-already-synthCopy head branch name to clipboard