Fix BFB export.
Fix BFB export.

markwal/CuraEngine,ROBO3D/CuraEngine,electrocbd/CuraEngine,mspark93/CuraEngine,jacobdai/CuraEngine-1,Ultimaker/CuraEngine,alex1818/CuraEngine,derekhe/CuraEngine,ROBO3D/CuraEngine,totalretribution/CuraEngine,derekhe/CuraEngine,patrick3coffee/CuraTinyG,foosel/CuraEngine,alephobjects/CuraEngine,alex1818/CuraEngine,ROBO3D/CuraEngine,markwal/CuraEngine,foosel/CuraEngine,markwal/CuraEngine,fxtentacle/CuraEngine,jacobdai/CuraEngine-1,alephobjects/CuraEngine,totalretribution/CuraEngine,electrocbd/CuraEngine,jacobdai/CuraEngine-1,fxtentacle/CuraEngine,electrocbd/CuraEngine,derekhe/CuraEngine,pratikshashroff/pcura,Ultimaker/CuraEngine,foosel/CuraEngine,uus169/CuraEngine,pratikshashroff/pcura,patrick3coffee/CuraTinyG,pratikshashroff/pcura,mspark93/CuraEngine,alex1818/CuraEngine,fxtentacle/CuraEngine,totalretribution/CuraEngine,uus169/CuraEngine,mspark93/CuraEngine,alephobjects/CuraEngine,uus169/CuraEngine,patrick3coffee/CuraTinyG