feat(util/rb_map): add erase_min
feat(util/rb_map): add erase_min

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