Don't give the union a name because it changes the mangled name.
Instead name the struct for __data.
* sysdeps/unix/sysv/linux/ia64/bits/pthreadtypes.h: Likewise.
* sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h: Likewise.
* sysdeps/unix/sysv/linux/s390/bits/pthreadtypes.h: Likewise.
* sysdeps/unix/sysv/linux/x86_64/bits/pthreadtypes.h: Likewise.
* pthread_create.c (start_thread): Adjust robust mutex free loop.
* descr.h (ENQUEUE_MUTEX, DEQUEUE_MUTEX): Adjust.