SCTP changes needed

Hi Michael,

As a followup to:
https://svnweb.freebsd.org/changeset/base/275358

Please find attached a separate SCTP patch as requested.

The attached patch re-enables flowids in the SCTP code as before. Until 
this patch is committed the SCTP code will not take full advantage of 
the multiple-transmit capabilities as found in many network adapters.

--HPS