zdtm: Fix race in locks08 test

The sub-process should wait for the parent task signal before
checking the locks status
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm/static/file_locks08.c

@@ -52,14 +52,18 @@ int main(int argc, char **argv)
 	int pid;
 	int status;
 	int ret = 0;
+	task_waiter_t tw;
 	struct flock lck;
 
 	test_init(argc, argv);
 	if (init_file_lock(&fd, &lck))
 		return -1;
 
+	task_waiter_init(&tw);
+
 	pid = fork();
 	if (pid == 0) {
+		task_waiter_wait4(&tw, getppid());
 		if (check_file_lock_restored(getpid(), fd, &lck) ||
 			check_lock_exists(filename, &lck) < 0)
 			ret = -1;
@@ -69,6 +73,8 @@ int main(int argc, char **argv)
 	test_daemon();
 	test_waitsig();
 
+	task_waiter_complete_current(&tw);
+
 	if (check_file_lock_restored(getpid(), fd, &lck) ||
 		check_lock_exists(filename, &lck) < 0)
 		fail("OFD file locks check failed\n");