Make sure EventPipe streaming thread won't write session->streaming_t…

…hread after session free. (#58710)

In case where ep_disable is called by a different thread (close IPC command)
there was a race between streaming threads setting
session->streaming_thread to NULL and IPC command triggering a call
to disable_holding_lock and freeing session.

Resetting the streaming_thread in streaming thread must happens before
it signals its shutdown event to prevent the race.

Co-authored-by: lateralusX <[email protected]>

src/native/eventpipe/ep-session.c

@@ -68,11 +68,10 @@ EP_RT_DEFINE_THREAD_FUNC (streaming_thread)
 			ep_rt_thread_sleep (timeout_ns);
 		}
 
+		session->streaming_thread = NULL;
 		ep_rt_wait_event_set (&session->rt_thread_shutdown_event);
 	EP_GCX_PREEMP_EXIT
 
-	session->streaming_thread = NULL;
-
 	if (!success)
 		ep_disable ((EventPipeSessionID)session);