idmap: Print error from idmap_backends_unixid_to_sid

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>
idmap: Store negative cache entries if the backend fails

This changes the behaviour for out-of-range queries: The tdb backend
(probably all backends) returns NT_STATUS_NONE_MAPPED and does not set the
map.status value to ID_UNMAPPED. This means that we did an early error
exit, not setting a negative cache value. This makes smbd ask winbind
over and over again for out-of-range gids, which can be a performance
problem in certain scenarios.

The new code makes us fall through to the code setting the negative
cache entry in all cases.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>

Autobuild-User(master): Michael Adam <obnox@samba.org>
Autobuild-Date(master): Fri May  3 14:48:35 CEST 2013 on sn-devel-104