Remove canary stuff

src/libexpr/eval.hh

@@ -287,8 +287,6 @@ public:
     /* Print statistics. */
     void printStats();
 
-    void printCanaries();
-
 private:
 
     unsigned long nrEnvs;
@@ -320,12 +318,6 @@ private:
     friend struct ExprOpConcatLists;
     friend struct ExprSelect;
     friend void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v);
-
-#if HAVE_BOEHMGC
-    std::set<Value *> gcCanaries;
-    friend void canaryFinalizer(GC_PTR obj, GC_PTR client_data);
-    friend void prim_gcCanary(EvalState & state, const Pos & pos, Value * * args, Value & v);
-#endif
 };