Mutex still locked at thread exit: mutex 0x........, recursion count 1, owner 3.
   at 0x........: pthread_join (drd_pthread_intercepts.c:?)
   by 0x........: main (tc22_exit_w_lock.c:43)
mutex 0x........ was first observed at:
   at 0x........: pthread_mutex_lock (drd_pthread_intercepts.c:?)
   by 0x........: child_fn1 (tc22_exit_w_lock.c:18)
   by 0x........: vgDrd_thread_wrapper (drd_pthread_intercepts.c:?)