vfs: Add inheritance emulation to vfs_nfs4acl_xattr.

vfs: Add inheritance emulation to vfs_nfs4acl_xattr.

Recursively inherit ACL from parent directory if no acl xattr is
found on the current file.
Use a default ACL if a non-inheriting ACL is encountered.
With this the nfs4acl_xattr.dynamic test passes.
But the nfs4acl_xattr.inheritance test results in an error because
of warnings that cause the test to pass a failed result.

Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>