rt: Add sanity checks when we hit the max task/port id

Author: brson

src/rt/rust_kernel.cpp

@@ -89,6 +89,7 @@ rust_kernel::register_task(rust_task *task) {
         task->user.id = max_task_id++;
         task_table.put(task->user.id, task);
     }
+    K(srv, task->user.id != INTPTR_MAX, "Hit the maximum task id");
     KLOG_("Registered task %" PRIdPTR, task->user.id);
     int new_live_tasks = sync::increment(live_tasks);
     KLOG_("Total outstanding tasks: %d", new_live_tasks);

src/rt/rust_task.cpp

@@ -628,6 +628,7 @@ rust_port_id rust_task::register_port(rust_port *port) {
     scoped_lock with(lock);
 
     rust_port_id id = next_port_id++;
+    A(thread, id != INTPTR_MAX, "Hit the maximum port id");
     port_table.put(id, port);
     return id;
 }