ice40: Speedup Arch::predictDelay() with pass-by-ref
ice40: Speedup Arch::predictDelay() with pass-by-ref

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