selftests/landlock: Fix build of audit_test

We are hitting build error on CentOS 9:

audit_test.c:232:40: error: ‘O_CLOEXEC’ undeclared (...)

Fix this by including fcntl.h.

Signed-off-by: Song Liu <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Fixes: 6b4566400a29 ("selftests/landlock: Add PID tests for audit records")
Signed-off-by: Mickaël Salaün <[e-mail]>

tools/testing/selftests/landlock/audit_test.c

···
 
 #define _GNU_SOURCE
 #include <errno.h>
+#include <fcntl.h>
 #include <limits.h>
 #include <linux/landlock.h>
 #include <pthread.h>