dbwrap_ctdb: Pass on mutex flags to tdb_open

Without this, ctdb can create a tdb file with mutex activated, but the
local tdb_open will not open the tdb due to strict flags checks whether
mutexes are possible.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=10922

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

Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Sun Nov 16 12:13:54 CET 2014 on sn-devel-104