criu: restore blocked signals correctly

We need to use SIG_SETMASK instead of SIG_BLOCK.

SIG_SETMASK
      The set of blocked signals is set to the argument set.
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

namespaces.c

@@ -1201,7 +1201,7 @@ int stop_usernsd(void)
 			ret = -1;
 
 		usernsd_pid = 0;
-		sigprocmask(SIG_BLOCK, &oldmask, NULL);
+		sigprocmask(SIG_SETMASK, &oldmask, NULL);
 
 		if (ret != 0)
 			pr_err("UNS: daemon exited abnormally\n");

sysctl.c

@@ -314,7 +314,7 @@ static int __userns_sysctl_op(void *arg, int proc_fd, pid_t pid)
 		kill(worker, SIGKILL);
 		goto out;
 	}
-	sigprocmask(SIG_BLOCK, &oldmask, NULL);
+	sigprocmask(SIG_SETMASK, &oldmask, NULL);
 
 	if (!WIFEXITED(status) || WEXITSTATUS(status)) {
 		pr_err("worker failed: %d\n", status);