[COMMITTED] [PATCH] PowerPC: Fix build due missing lll_robust_trylock

[Adhemerval Zanella]

Commit 887865f remove the lll_robust_trylock definition on all
architectures, however for powerpc both __lll_trylock and
__lll_cond_trylock were based on lll_robust_trylock definition.
It breaks powerpc build with a missing lll_robust_trylock due:

--

In file included from ../include/errno.h:27:0,
                 from ../sysdeps/pthread/ftrylockfile.c:19:
../sysdeps/pthread/ftrylockfile.c: In function ‘__ftrylockfile’:
../sysdeps/powerpc/nptl/tls.h:93:45: warning: implicit declaration of function ‘__lll_robust_trylock’ [-Wimplicit-function-declaration]
 # define TLS_TCB_ALIGN  __alignof__ (struct pthread)
                                             ^
../sysdeps/powerpc/nptl/tls.h:98:52: note: in expansion of macro ‘TLS_TCB_ALIGN’
    + ((sizeof (tcbhead_t) + TLS_TCB_ALIGN - 1) & ~(TLS_TCB_ALIGN - 1)))
                                                    ^
../sysdeps/powerpc/nptl/tls.h:146:24: note: in expansion of macro ‘TLS_PRE_TCB_SIZE’
     - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE))
                        ^
../sysdeps/nptl/bits/stdio-lock.h:53:20: note: in expansion of macro ‘THREAD_SELF’
     void *__self = THREAD_SELF;            \
                    ^
../sysdeps/pthread/ftrylockfile.c:29:10: note: in expansion of macro ‘_IO_lock_trylock’
   return _IO_lock_trylock (*stream->_lock);

--

This patch restore it with a different name.

Checked on powerpc64be and powerpc64le.  I would advise architecture maintainers
to check build on other arches as well.