rt: Move the addition of the stack canary into create_stack

src/rt/rust_task.cpp

@@ -593,7 +593,6 @@ rust_task::new_stack(size_t requested_sz) {
     size_t sz = rust_stk_sz + RED_ZONE_SIZE;
     stk_seg *new_stk = create_stack(this, sz);
     LOGPTR(thread, "new stk", (uintptr_t)new_stk);
-    add_stack_canary(new_stk);
     new_stk->prev = NULL;
     new_stk->next = stk;
     LOGPTR(thread, "stk end", new_stk->end);