Fix test coverage problem by forcing to use gcov-4.8
Fix test coverage problem by forcing to use gcov-4.8

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