Start the process of tvbuffifying the SMB dissector - give it a

Start the process of tvbuffifying the SMB dissector - give it a
tvbuffified heuristic-dissector interface, but have it immediately turn
its arguments into an old-style buffer pointer and offset.

Register the SMB dissector as a heuristic NetBIOS dissector, and have
"dissect_netbios_payload()" just try the heuristics, as it no longer has
to call the SMB dissector explicitly.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@3973 f5534014-38df-0310-8fa8-9805f1628bb7