lil fix: don't compute overhang on first layer
lil fix: don't compute overhang on first layer

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