LU-14291 lustre: further cleanup of acl code.

LU-14291 lustre: further cleanup of acl code.

Code in lustre/obdclass/acl.c is only used in lustre/mdd/, so move the
file there, renaming to mdd_acl.c and removing EXPORT_SYMBOL()
declarations.

The function prototypes in lustre_eacl.h are moved to mdd_internal.h,
and the remainder of that file is discarded.  THe
HAVE_STRUCT_ACL_XATTR stanza, in particular, is unnecessary is it
exists in lustre_compat.h.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Idb0978758640c5ad527d2c68c4fdf6dee32a731c
Reviewed-on: https://review.whamcloud.com/42032
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>