MINOR: checks: Don't use a static tcp rule list head

MINOR: checks: Don't use a static tcp rule list head

To allow reusing these blocks without consuming more memory, their list
should be static and share-able accross uses. The head of the list will
be shared as well.

It is thus necessary to extract the head of the rule list from the proxy
itself. Transform it into a pointer instead, that can be easily set to
an external dynamically allocated head.