selftests/filesystems: Fix build of anon_inode_test

selftests/filesystems: Fix build of anon_inode_test

The newly added anon_inode_test test fails to build due to attempting to
include a nonexisting overlayfs/wrapper.h:

  anon_inode_test.c:10:10: fatal error: overlayfs/wrappers.h: No such file or directory
     10 | #include "overlayfs/wrappers.h"
        |          ^~~~~~~~~~~~~~~~~~~~~~

This is due to 0bd92b9fe538 ("selftests/filesystems: move wrapper.h out
of overlayfs subdir") which was added in the vfs-6.16.selftests branch
which was based on -rc5 and did not contain the newly added test so once
things were merged into mainline the build started failing - both parent
commits are fine.

Fixes: 3e406741b1989 ("Merge tag 'vfs-6.16-rc1.selftests' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs")
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>