* thread.cc (pthread_mutex::initMutex): Use the wrapper init call.
(pthread_mutex::nativeMutex::init): Implement.
(pthread_mutex::nativeMutex::lock): Ditto.
(pthread_mutex::nativeMutex::unlock): Ditto.
(pthread_mutex::init): Use the wrapper lock and unlockcalls.
* thread.h (pthread_mutex): Move mutexInitializationLock into a
nativeMutex wrapper class.