This example demonstrate the use of mutexes in RTLinux programs.The Linux init_module() function creates three threads that try to competefor the mutex.  After successfully locking the mutex, each thread waitsfor 500ms, and then unlocks the mutex.The times spent in pthread_mutex_lock are reportedto show that the RT-threads actually block.To run the example, type make test. You have to be at a Linux console (no X)to see the results.