nptl: Replace __futex_clocklock_wait64 with __futex_abstimed_wait64

For non null timeouts, the __futex_clocklock_wait64 creates an a
relative timeout by subtracting the current time from the input
argument.  The same behavior can be obtained with FUTEX_WAIT_BITSET
without the need to calculate the relative timeout.  Besides consolidate
the code it also avoid the possible relative timeout issues [1].

The __futex_abstimed_wait64 needs also to return EINVAL syscall
errors.

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

[1] https://sourceware.org/pipermail/libc-alpha/2020-November/119881.html

Reviewed-by: Lukasz Majewski <lukma@denx.de>

nptl/pthread_mutex_timedlock.c

@@ -391,8 +391,8 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
 		/* Delay the thread until the timeout is reached. Then return
 		   ETIMEDOUT.  */
 		do
-		  e = __futex_clocklock_wait64 (&(int){0}, 0, clockid, abstime,
-		                                private);
+		  e = __futex_abstimed_wait64 (&(unsigned int){0}, 0, clockid,
+					       abstime, private);
 		while (e != ETIMEDOUT);
 		return ETIMEDOUT;
 	      }