Fix a copy and paste error.

X-MFC with: 269436
Add support for the SCTP_PR_SUPPORTED socket option as specified in
http://tools.ietf.org/html/draft-ietf-tsvwg-sctp-prpolicies
Add also a sysctl controlling the default of the end-points.

MFC after: 1 week
Rework r269444 to work also for lists without IDs.

MFC after:	3 days
Report SPC-4 XCOPY capabilities (not yet implemented).
Implement PT and RRTI.
Add first pieces of WUT.