fix(library/blast/blast): compilation warning on OSX
fix(library/blast/blast): compilation warning on OSX

leodemoura/lean,digama0/lean,digama0/lean,UlrikBuchholtz/lean,dselsam/lean,javra/lean,dselsam/lean,levnach/lean,avigad/lean,levnach/lean,soonhokong/lean-osx,avigad/lean,leodemoura/lean,leanprover-community/lean,javra/lean,digama0/lean,Kha/lean,rlewis1988/lean,fpvandoorn/lean,leanprover/lean,Kha/lean,soonhokong/lean,leanprover/lean,UlrikBuchholtz/lean,johoelzl/lean,soonhokong/lean,leodemoura/lean,fpvandoorn/lean,levnach/lean,digama0/lean,fgdorais/lean,leanprover-community/lean,leanprover/lean,UlrikBuchholtz/lean,fpvandoorn/lean2,fpvandoorn/lean2,javra/lean,leanprover-community/lean,avigad/lean,fgdorais/lean,fpvandoorn/lean,leanprover-community/lean,javra/lean,dselsam/lean,leodemoura/lean,leanprover/lean,fgdorais/lean,dselsam/lean,leodemoura/lean,johoelzl/lean,soonhokong/lean,UlrikBuchholtz/lean,soonhokong/lean-osx,javra/lean,rlewis1988/lean,fpvandoorn/lean2,rlewis1988/lean,fpvandoorn/lean2,johoelzl/lean,fgdorais/lean,fpvandoorn/lean,levnach/lean,avigad/lean,soonhokong/lean-windows,soonhokong/lean-windows,soonhokong/lean-windows,soonhokong/lean-osx,soonhokong/lean,fgdorais/lean,Kha/lean,fgdorais/lean,fpvandoorn/lean,digama0/lean,Kha/lean,leodemoura/lean,leanprover-community/lean,digama0/lean,avigad/lean,dselsam/lean,leanprover/lean,johoelzl/lean,levnach/lean,rlewis1988/lean,Kha/lean,rlewis1988/lean,soonhokong/lean-osx,rlewis1988/lean,Kha/lean,johoelzl/lean,leanprover/lean,soonhokong/lean-windows,soonhokong/lean-windows,fpvandoorn/lean,dselsam/lean,avigad/lean,fpvandoorn/lean2,UlrikBuchholtz/lean,leanprover-community/lean,soonhokong/lean-osx,soonhokong/lean,johoelzl/lean