python:tdb_util: "samba-tool domain backup offline" hangs

python:tdb_util: "samba-tool domain backup offline" hangs

GNU getopt(3) is by default non-POSIX compliant and accepts options after
positional arguments (unless forced with POSIXLY_CORRECT). This is not portable,
e..g., on FreeBSD. Put options first and then positional arguments.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15804

Signed-off-by: Andrea Venturoli <ml@netfence.it>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Jennifer Sutton <jennifersutton@catalyst.net.nz>