r11338: Move knowledge of \\ needed into rpc_client/cli_netlogon

r11338: Move knowledge of \\ needed into rpc_client/cli_netlogon
(this is the way it's been done in other functions). Instead
of moving this into the IDL, I think the best solution would
be to write a wrapper function around any call that needs
this (this is what we already do for many of the calls).
Jeremy.