rt: Add an on-the-side GC chain

src/rt/rust_task.h

@@ -5,6 +5,8 @@
 #ifndef RUST_TASK_H
 #define RUST_TASK_H
 
+#include <map>
+
 #include "util/array_list.h"
 
 #include "context.h"
@@ -113,6 +115,8 @@ rust_task : public kernel_owned<rust_task>, rust_cond
 
     rust_obstack dynastack;
 
+    std::map<void *,type_desc *> local_allocs;
+
     // Only a pointer to 'name' is kept, so it must live as long as this task.
     rust_task(rust_scheduler *sched,
               rust_task_list *state,