ntdll: Fix its vs it's typos.

dlls/ntdll/sync.c

@@ -1537,7 +1537,7 @@ DWORD WINAPI RtlRunOnceExecuteOnce( RTL_RUN_ONCE *once, PRTL_RUN_ONCE_INIT_FN fu
  * purposes. The following table lists all possible states the lock can be
  * in, notation: [X, #exclusive, #shared]:
  *
- * [0,   0,   N] -> locked by N shared access threads, if N=0 its unlocked
+ * [0,   0,   N] -> locked by N shared access threads, if N=0 it's unlocked
  * [0, >=1, >=1] -> threads are requesting exclusive locks, but there are
  * still shared access threads inside. #shared should not be incremented
  * anymore!

dlls/ntdll/threadpool.c

@@ -1217,7 +1217,7 @@ static void CALLBACK timerqueue_thread_proc( void *param )
             timer->u.timer.timer_pending = FALSE;
             tp_object_submit( timer, FALSE );
 
-            /* Insert the timer back into the queue, except its marked for shutdown. */
+            /* Insert the timer back into the queue, except it's marked for shutdown. */
             if (timer->u.timer.period && !timer->shutdown)
             {
                 timer->u.timer.timeout += (ULONGLONG)timer->u.timer.period * 10000;