fix(builtin/heq): extensionality axioms
fix(builtin/heq): extensionality axioms

Signed-off-by: Leonardo de Moura <7610bae85f2b530654cc716772f1fe653373e892@microsoft.com>

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