Fix comparison between long and int64_t
Fix comparison between long and int64_t

On some machines, long isn't 64-bit.

Contributes to issue CURA-2296.

alephobjects/CuraEngine,ROBO3D/CuraEngine,ROBO3D/CuraEngine,Ultimaker/CuraEngine,alephobjects/CuraEngine,Ultimaker/CuraEngine,alephobjects/CuraEngine,ROBO3D/CuraEngine