Remove unused typedef and field

Author: Ericson2314

src/libstore/include/nix/store/build/drv-output-substitution-goal.hh

@@ -35,8 +35,6 @@ public:
         RepairFlag repair = NoRepair,
         std::optional<ContentAddress> ca = std::nullopt);
 
-    typedef void (DrvOutputSubstitutionGoal::*GoalState)();
-    GoalState state;
 
     Co init();
     Co realisationFetched(Goals waitees, std::shared_ptr<const Realisation> outputInfo, nix::ref<nix::Store> sub);