vfs_fruit: fix close for fake_fd

vfs_fruit: fix close for fake_fd

If the next backend doesn't use kernel fd's should not
pass a fake_fd to the next backend.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14596

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Fri Jan  8 21:38:18 UTC 2021 on sn-devel-184

(back-ported from commit 564b62a6f7c0a9b9712946d723118122b9c3785f)

Autobuild-User(v4-12-test): Karolin Seeger <kseeger@samba.org>
Autobuild-Date(v4-12-test): Wed Jan 13 13:45:00 UTC 2021 on sn-devel-184