SCTP and MSG_MORE

I hadn't realised that linux had a MSG_MORE exposed to userland...

The sctp stack could usefully use it to get multiple data chunks
into a single ethernet frame.

Currently it is very difficult to get more than one data chunk in
an ethernet frame which means that the ethernet packet rate is
much higher than it would be if the same traffic were sent using TCP.

I don't know enough about the SCTP code to even start looking for
where this might be implemented.  It might be almost trivial...

	David