Function runtime_work_pending 

pub fn runtime_work_pending() -> bool

Non-blocking poll for the window between begin_shutdown and finish_shutdown: false means phase 2 will not wait for user work.

Answers for the running generation when no shutdown is outstanding.

It never waits for a lock either: when another thread holds one it reads under, it answers true and the host polls again on its next turn. That keeps a pool thread that died holding such a lock (a trap on wasm32-wasip1-threads unwinds nothing) from parking the polling thread for good.