r3145: Add experimental idmap_rid-Plugin.

r3145: Add experimental idmap_rid-Plugin.

Written by Sumit Bose <sbose@suse.de> and myself a while ago.

idmap_rid does a direct, static mapping between RIDs and UIDs/GIDs using
the idmap-range as offset. It does thus allow to have a unified mapping
over several winbindd-systems without having the need of a central
LDAP-Server (and all related dependencies and problems this solution can
bring).

Compile:
./configure --with-shared-modules=idmap_rid

Usage:
        idmap backend = idmap_rid

idmp_rid does even allow you to have multiple mappings (for trusted
domains). This is a rather problemtic feature and will be turned off by
default rather soon. The problem is that ranges can quickly overlap when
not measured with caution.

        idmap backend = idmap_rid:"MYDOMAIN=1000-9999 OTHER=10000-19999"

Will valgrind idmap_rid later today and fix a couple of things.

Guenther
(This used to be commit 49a238bd37105bf1a33d4a230ca594c4cf304dd3)