nptl: Replace non cancellable pause/nanosleep with futex

To help y2038 work avoid duplicate all the logic of nanosleep on
non cancellable version, the patch replace it with a new futex
operation, lll_timedwait.  The changes are:

  - Add a expected value for __lll_clocklock_wait, so it can be used
    to wait for generic values.

  - Remove its internal atomic operation and move the logic to
    __lll_clocklock.  It makes __lll_clocklock_wait even more generic
    and __lll_clocklock slight faster on fast-path (since it won't
    require a function call anymore).

  - Add lll_timedwait, which uses __lll_clocklock_wait, to replace both
    __pause_nocancel and __nanosleep_nocancel.

It also allows remove the sparc32 __lll_clocklock_wait implementation
(since it is similar to the generic one).

Checked on x86_64-linux-gnu, sparcv9-linux-gnu, and i686-linux-gnu.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

nptl/pthread_mutex_lock.c

@@ -434,7 +434,8 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex)
 
 		/* Delay the thread indefinitely.  */
 		while (1)
-		  __pause_nocancel ();
+		  lll_timedwait (&(int){0}, 0, 0 /* ignored */, NULL,
+				 private);
 	      }
 
 	    oldval = mutex->__data.__lock;