dccp: Implement lookup table for feature-negotiation information

A lookup table for feature-negotiation information, extracted from RFC
4340/42, is provided by this patch. All currently known features can
be found in this table, along with their feature location, their
default value, and type.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>