core/make_task: Implement lambda_task::waiting_task()
core/make_task: Implement lambda_task::waiting_task()

avikivity/seastar,scylladb/seastar,scylladb/seastar,dreamsxin/seastar,avikivity/seastar,scylladb/seastar,syuu1228/seastar,cloudius-systems/seastar,cloudius-systems/seastar,dreamsxin/seastar,syuu1228/seastar,dreamsxin/seastar,avikivity/seastar,syuu1228/seastar,cloudius-systems/seastar