Fix OSX linker warning issue
Fix OSX linker warning issue

javra/lean,eigengrau/lean,Kha/lean,rlewis1988/lean,UlrikBuchholtz/lean,c-cube/lean,levnach/lean,codyroux/lean0.1,fpvandoorn/lean,sp3ctum/lean,leanprover-community/lean,soonhokong/travis_test,johoelzl/lean,levnach/lean,codyroux/lean0.1,htzh/lean,leanprover/lean,avigad/lean,fgdorais/lean,levnach/lean,c-cube/lean,leanprover-community/lean,htzh/lean,rlewis1988/lean,leanprover/lean,digama0/lean,avigad/lean,fpvandoorn/lean2,c-cube/lean,fpvandoorn/lean2,fpvandoorn/lean,htzh/lean,javra/lean,leanprover-community/lean,fpvandoorn/lean,leodemoura/lean,javra/lean,Kha/lean,soonhokong/lean-osx,soonhokong/lean-osx,codyroux/lean0.1,htzh/lean,rlewis1988/lean,soonhokong/travis_test,fgdorais/lean,soonhokong/lean,soonhokong/lean,johoelzl/lean,soonhokong/lean-osx,leodemoura/lean,c-cube/lean,eigengrau/lean,leodemoura/lean,c-cube/lean,rlewis1988/lean,UlrikBuchholtz/lean,soonhokong/lean,leodemoura/lean,soonhokong/lean-windows,soonhokong/lean-windows,leanprover-community/lean,fgdorais/lean,htzh/lean,sp3ctum/lean,dselsam/lean,leanprover/lean,soonhokong/lean-windows,eigengrau/lean,eigengrau/lean,Kha/lean,sp3ctum/lean,soonhokong/lean,UlrikBuchholtz/lean,soonhokong/lean-windows,rlewis1988/lean,Kha/lean,fpvandoorn/lean2,Kha/lean,levnach/lean,johoelzl/lean,avigad/lean,leodemoura/lean,digama0/lean,fpvandoorn/lean,dselsam/lean,fpvandoorn/lean,soonhokong/travis_test,sp3ctum/lean,dselsam/lean,leanprover/lean,sp3ctum/lean,soonhokong/lean-osx,leanprover/lean,johoelzl/lean,leanprover/lean,leanprover-community/lean,soonhokong/lean-windows,digama0/lean,javra/lean,avigad/lean,leanprover-community/lean,dselsam/lean,fgdorais/lean,fgdorais/lean,fpvandoorn/lean2,digama0/lean,codyroux/lean0.1,johoelzl/lean,levnach/lean,soonhokong/lean-osx,UlrikBuchholtz/lean,soonhokong/travis_test,rlewis1988/lean,avigad/lean,digama0/lean,dselsam/lean,javra/lean,fpvandoorn/lean2,soonhokong/lean,avigad/lean,dselsam/lean,digama0/lean,eigengrau/lean,johoelzl/lean,fgdorais/lean,leodemoura/lean,Kha/lean,fpvandoorn/lean,UlrikBuchholtz/lean