feat(frontends/lean/pp_options): use a more effective get_distinguishing_pp_options
feat(frontends/lean/pp_options): use a more effective get_distinguishing_pp_options

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

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