ipc,sem: use current->state helpers

Call __set_current_state() instead of assigning the new state directly.
These interfaces also aid CONFIG_DEBUG_ATOMIC_SLEEP environments, keeping
track of who changed the state.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ipc/sem.c

@@ -1941,7 +1941,7 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
 	queue.sleeper = current;
 
 sleep_again:
-	current->state = TASK_INTERRUPTIBLE;
+	__set_current_state(TASK_INTERRUPTIBLE);
 	sem_unlock(sma, locknum);
 	rcu_read_unlock();