sysctl: restore sysctl-vs synchronously

CRIU sets kernel/sem_next_id to retore semaphores and
this sysctl should be set berore semget().

(00.550616)      1: UNS: calling 0x443f70 (15, 1)
(00.551077)      1: Error (ipc_ns.c:573): Failed to restore sem id (0 instead of 65536)
(00.551251)      1: Error (ipc_ns.c:627): Failed to prepare semaphores set

Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Tycho Andersen <tycho.andersen@canonical.com>
Reported-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

sysctl.c

@@ -457,7 +457,7 @@ int sysctl_op(struct sysctl_req *req, size_t nr_req, int op, unsigned int ns)
 	if (fd < 0)
 		return -1;
 
-	ret = userns_call(__userns_sysctl_op, UNS_ASYNC, userns_req, MAX_UNSFD_MSG_SIZE, fd);
+	ret = userns_call(__userns_sysctl_op, 0, userns_req, MAX_UNSFD_MSG_SIZE, fd);
 	close(fd);
 	return ret;
 }