s3-dcerpc: avoid talloc_move on schannel creds in cli_rpc_pipe_open_schannel_with_key().

s3-dcerpc: avoid talloc_move on schannel creds in cli_rpc_pipe_open_schannel_with_key().

Initially, the schannel creds were talloc memduped, then, during the netlogon
creds client merge (baf7274fed2f1ae7a9e3a57160bf5471566e636c) they were first
talloc_referenced and then later (53765c81f726a8c056cc4e57004592dd489975c9)
talloc_moved.

The issue with using talloc_move here is that users of that function in winbind
will only be able to have two schanneled connections, as the cached schannel
credentials pointer from the netlogon pipe will be set to NULL. Do a deep copy
of the struct instead.

Guenther