libcli/auth: avoid using transactions a chainlock is enough

We're just writting a single record into a CLEAR_IF_FIRST|TDB_NOSYNC
tdb.

We just need to make sure we lock the record between reading and writting.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>

Autobuild-User(master): Volker Lendecke <vl@samba.org>
Autobuild-Date(master): Thu Mar 28 14:52:14 CET 2013 on sn-devel-104
Optimization suggested by Volker. Don't do a stat system call on normal read path.

Only do it if we need it in the sendfile() path.

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>

Autobuild-User(master): Volker Lendecke <vl@samba.org>
Autobuild-Date(master): Thu Mar 28 17:51:22 CET 2013 on sn-devel-104
Make sure that we only propogate the INHERITED flag when we are allowed to.

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Richard Sharpe <realrichardsharpe@gmail.com>

Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Thu Mar 28 19:43:41 CET 2013 on sn-devel-104