r13545: A patch which I think it's time has come. VOlker, we can talk about
this more but it gets around the primary group issue.
* don't map a SID to a name from the group mapping code if
the map doesn't have a valid gid. This is only an issue
in a tdb setup
* Always allow S-1-$DOMAIN-513 to resolve (just like Windows)
* if we cannot resolve a users primary GID to a SID, then set
it to S-1-$DOMAIN-513
* Ignore the primary group SID inside pdb_enum_group_memberships().
Only look at the Unix group membersip.
Jeremy, this fixes a fresh install startup for smbd as far as my tests
are concerned.