Merge tag 'vfs-6.16-rc1.selftests' of git://git.kernel.org/pub/scm/linux/kernel/git...

Pull vfs selftests updates from Christian Brauner:
 "This contains various cleanups, fixes, and extensions for out
  filesystem selftests"

* tag 'vfs-6.16-rc1.selftests' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  selftests/fs/mount-notify: add a test variant running inside userns
  selftests/filesystems: create setup_userns() helper
  selftests/filesystems: create get_unique_mnt_id() helper
  selftests/fs/mount-notify: build with tools include dir
  selftests/mount_settattr: remove duplicate syscall definitions
  selftests/pidfd: move syscall definitions into wrappers.h
  selftests/fs/statmount: build with tools include dir
  selftests/filesystems: move wrapper.h out of overlayfs subdir
  selftests/mount_settattr: ensure that ext4 filesystem can be created
  selftests/mount_settattr: add missing STATX_MNT_ID_UNIQUE define
  selftests/mount_settattr: don't define sys_open_tree() twice