Fix building libclipper.a all the time after #76
Fix building libclipper.a all the time after #76

alephobjects/CuraEngine,patrick3coffee/CuraTinyG,jacobdai/CuraEngine-1,Ultimaker/CuraEngine,robotustra/curax,patrick3coffee/CuraTinyG,alephobjects/CuraEngine,markwal/CuraEngine,fxtentacle/CuraEngine,robotustra/curax,derekhe/CuraEngine,fxtentacle/CuraEngine,foosel/CuraEngine,uus169/CuraEngine,pratikshashroff/pcura,Skeen/CuraJS-Engine,electrocbd/CuraEngine,totalretribution/CuraEngine,ROBO3D/CuraEngine,foosel/CuraEngine,daid/CuraCutEngine,daid/CuraCutEngine,markwal/CuraEngine,alex1818/CuraEngine,ROBO3D/CuraEngine,be3d/CuraEngine,Skeen/CuraJS-Engine,uus169/CuraEngine,pratikshashroff/pcura,robotustra/curax,pratikshashroff/pcura,Ultimaker/CuraEngine,mspark93/CuraEngine,markwal/CuraEngine,electrocbd/CuraEngine,be3d/CuraEngine,patrick3coffee/CuraTinyG,Jwis921/PersonalCuraEngine,mspark93/CuraEngine,uus169/CuraEngine,foosel/CuraEngine,phonyphonecall/CuraEngine,alex1818/CuraEngine,phonyphonecall/CuraEngine,phonyphonecall/CuraEngine,jacobdai/CuraEngine-1,Jwis921/PersonalCuraEngine,be3d/CuraEngine,Jwis921/PersonalCuraEngine,alex1818/CuraEngine,jacobdai/CuraEngine-1,electrocbd/CuraEngine,totalretribution/CuraEngine,derekhe/CuraEngine,totalretribution/CuraEngine,derekhe/CuraEngine,Skeen/CuraJS-Engine,ROBO3D/CuraEngine,alephobjects/CuraEngine,fxtentacle/CuraEngine,mspark93/CuraEngine