Partly based on the work by mimir (Rafal Szczesniak

Partly based on the work by mimir (Rafal Szczesniak
<mimir@diament.ists.pwr.wroc.pl>) this patch allows samba to correctly
enumerate its trusted domains - by exaimining the keys in the secrets.tdb file.

This patch has been tested with both NT4 and rpcclient/wbinfo, and adds
some extra functionality to talloc and rpc_parse to allow it to deal with
already unicode strings.

Finally, this cleans up some const warnings that were in net_rpc.c by pushing
another dash of const into the rpc client code.

Andrew Bartlett