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 <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

tools/testing/selftests/filesystems/anon_inode_test.c

···
 #include <sys/stat.h>
 
 #include "../kselftest_harness.h"
-#include "overlayfs/wrappers.h"
+#include "wrappers.h"
 
 TEST(anon_inode_no_chown)
 {