MAJOR: acl: convert all ACL requires to SMP use+val instead of ->requires

MAJOR: acl: convert all ACL requires to SMP use+val instead of ->requires

The ACLs now use the fetch's ->use and ->val to decide upon compatibility
between the place where they are used and where the information are fetched.
The code is capable of reporting warnings about very fine incompatibilities
between certain fetches and an exact usage location, so it is expected that
some new warnings will be emitted on some existing configurations.

Two degrees of detection are provided :
  - detecting ACLs that never match
  - detecting keywords that are ignored

All tests show that this seems to work well, though bugs are still possible.