Added the build directory to .gitignore
Added the build directory to .gitignore

YosysHQ/nextpnr,YosysHQ/nextpnr,YosysHQ/nextpnr,YosysHQ/nextpnr,SymbiFlow/nextpnr,SymbiFlow/nextpnr,SymbiFlow/nextpnr,SymbiFlow/nextpnr