[DCCP]: Set the default CCID according to kernel config selection

Now CCID2 is the default, as stated in the RFC drafts, but we allow
a config where just CCID3 is built, where CCID3 becomes the default.

Signed-off-by: Ian McDonald <imcdnzl@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>