* pthread.c (__pthread_initialize_manager): Subtract
TLS_PRE_TCB_SIZE bytes from tcbp to get to descr.
* manager.c (pthread_handle_create): Subtract or add TLS_PRE_TCB_SIZE
instead of sizeof (pthread_descr).
(pthread_free): Add TLS_PRE_TCB_SIZE instead of sizeof (pthread_descr).
* sysdeps/powerpc/tls.h (TLS_INIT_TCB_SIZE, TLS_TCB_SIZE): Define to 0.