* internals.h: Define THREAD_GETMEM and THREAD_SETMEM to default if
not already defined.
(struct _pthread_descr_struct): Add p_self and p_nr field.
* manager.c (__pthread_handles): Define second element to point
to manager thread.
(__pthread_handles_num): Initialize to 2.
(__pthread_manager): Use INIT_THREAD_SELF with two arguments.
(pthread_start_thread): Likewise.
(pthread_handle_create): Start search for free slot at entry 2.
Initialize new fields p_self and p_nr.
Call __clone with CLONE_PTRACE if available.
(pthread_free): Call FREE_THREAD_SELF if available.
* pthread.c (__pthread_initial_thread): Initialize new fields.
(__pthread_manager_thread): Likewise.
(__pthread_initialize_manager): Call __clone with CLONE_PTRACE.
* cancel.c: Use THREAD_GETMEM and THREAD_SETMEM to access the
elements of the thread descriptor.
* condvar.c: Likewise.
* errno.c: Likewise.
* join.c: Likewise.
* manager.c: Likewise.
* pthread.c: Likewise.
* ptlongjmp.c: Likewise.
* semaphore.c: Likewise.
* signals.c: Likewise.
* specific.c: Likewise.
* spinlock.c: Likewise.
* sysdeps/alpha/pt-machine.h (INIT_THREAD_SELF): Add extra parameter.
* sysdeps/i386/useldt.h: New file.
* sysdeps/i386/i686/pt-machine.h: Show how to use this file.
* sysdeps/sparc/sparc32/pt-machine.h: Define THREAD_GETMEM and
THREAD_SETMEM using __thread_self.
* sysdeps/sparc/sparc64/pt-machine.h: Likewise.