[XFS] Fix up problem when CONFIG_XFS_POSIX_ACL is not set and yet we still

can use the _ACL_TYPE_* definitions in linux-2.6/xfs_xattr.c. The
forthcoming generic acl code will also fix this problem.

SGI-PV: 982343

SGI-Modid: xfs-linux-melb:xfs-kern:31369a

Signed-off-by: Tim Shimmin <tes@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>