Update src/concurrency/thread.rs

Co-authored-by: Ralf Jung <[email protected]>

src/concurrency/thread.rs

@@ -647,8 +647,7 @@ impl<'tcx> ThreadManager<'tcx> {
                     @capture<'tcx> {
                         joined_thread_id: ThreadId,
                     }
-                    @unblock = |this, tcb_state| {
-                        match tcb_state {
+                    @unblock = |this, unblock| {
                             MachineCallbackState::Ready => {
                                 if let Some(data_race) = &mut this.machine.data_race {
                                     data_race.thread_joined(&this.machine.threads, joined_thread_id);