pthreadpool: Remove wrong comment.

Commit e45d33e removed the sync fallback path for the case that no
thread could be created. Remove the comment for that fallback as it does
not make sense anymore.

Signed-off-by: Christof Schmitt <cs@samba.org>
Reviewed-by: Ralph Böhme <slow@samba.org>

Autobuild-User(master): Christof Schmitt <cs@samba.org>
Autobuild-Date(master): Fri Aug 23 23:09:12 UTC 2019 on sn-devel-184

lib/pthreadpool/pthreadpool.c

@@ -806,10 +806,6 @@ int pthreadpool_add_job(struct pthreadpool *pool, int job_id,
 		return 0;
 	}
 
-	/*
-	 * No thread could be created to run job, fallback to sync
-	 * call.
-	 */
 	pthreadpool_undo_put_job(pool);
 
 	unlock_res = pthread_mutex_unlock(&pool->mutex);