Remove richacl support

Remove richacl support

There's no support for richacl in Linux and based on information in the
links will never be. Remove all related files and support code.

References:
- https://wiki.samba.org/index.php/NFS4_ACL_overview#Linux
- https://lwn.net/Articles/661357/ (article, 2015)
- https://lwn.net/Articles/661078/ (patches, 2015)
- https://github.com/andreas-gruenbacher/richacl/
- http://www.bestbits.at/richacl/ (n/a anymore)

Signed-off-by: David Sterba <dsterba@suse.com>
Reviewed-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>