[inductor] subproc parallel compile: initialize future before sending…

… work to the pool (pytorch#128086)

Summary: I got reports of intermittent failures in CI and the logs show errors like this:
```
CRITICAL:concurrent.futures:Future 139789013754560 in unexpected state: FINISHED
```
I can't repro locally, but seems clear that we should initialize the future _before_ sending work to the subprocess pool since it could finish before we call set_running_or_notify_cancel()

Differential Revision: [D58239829](https://our.internmc.facebook.com/intern/diff/D58239829)
Pull Request resolved: pytorch#128086
Approved by: https://github.com/jansel
ghstack dependencies: pytorch#128037

torch/_inductor/compile_worker/subproc_pool.py

@@ -109,11 +109,11 @@ def submit(self, job_fn: Callable[..., Any], *args):
         with self.futures_lock:
             job_id = next(self.job_id_count)
             self.pending_futures[job_id] = future = Future()
+        future.set_running_or_notify_cancel()
         with self.write_lock:
             if not self.running:
                 raise RuntimeError("submit() on closed pool")
             _send_msg(self.write_pipe, job_id, job_data)
-        future.set_running_or_notify_cancel()
         return future
 
     def _read_thread(self):