generalize insert-backedges to insert in any world

Rather than a binary valid/not-valid, we track the exact later world
that deleted it, relative to when we first assumed it may be valid.

Author: vtjnash

src/staticdata.c

@@ -2243,6 +2243,7 @@ static void jl_prepare_serialization_data(jl_array_t *mod_array, jl_array_t *new
     }
 
     if (edges) {
+        size_t world = jl_atomic_load_acquire(&jl_world_counter);
         jl_collect_missing_backedges(jl_type_type_mt);
         jl_collect_missing_backedges(jl_nonfunction_mt);
         // jl_collect_extext_methods_from_mod and jl_collect_missing_backedges also accumulate data in callers_with_edges.
@@ -2252,7 +2253,7 @@ static void jl_prepare_serialization_data(jl_array_t *mod_array, jl_array_t *new
         *method_roots_list = jl_alloc_vec_any(0);
         // Collect the new method roots
         jl_collect_new_roots(*method_roots_list, *new_specializations, worklist_key);
-        jl_collect_edges(*edges, *ext_targets, *new_specializations);
+        jl_collect_edges(*edges, *ext_targets, *new_specializations, world);
     }
     assert(edges_map == NULL); // jl_collect_edges clears this when done
 
@@ -3270,7 +3271,8 @@ static jl_value_t *jl_restore_package_image_from_stream(ios_t *f, jl_image_t *im
             // Add roots to methods
             jl_copy_roots(method_roots_list, jl_worklist_key((jl_array_t*)restored));
             // Handle edges
-            jl_insert_backedges((jl_array_t*)edges, (jl_array_t*)ext_targets, (jl_array_t*)new_specializations); // restore external backedges (needs to be last)
+            size_t world = jl_atomic_load_acquire(&jl_world_counter);
+            jl_insert_backedges((jl_array_t*)edges, (jl_array_t*)ext_targets, (jl_array_t*)new_specializations, world); // restore external backedges (needs to be last)
             // reinit ccallables
             jl_reinit_ccallable(&ccallable_list, base, NULL);
             arraylist_free(&ccallable_list);