MEDIUM: acl: remove flag ACL_MAY_LOOKUP which is improperly used

MEDIUM: acl: remove flag ACL_MAY_LOOKUP which is improperly used

This flag is used on ACL matches that support being looking up patterns
in trees. At the moment, only strings and IPs support tree-based lookups,
but the flag is randomly set also on integers and binary data, and is not
even always set on strings nor IPs.

Better get rid of this mess by only relying on the matching function to
decide whether or not it supports tree-based lookups, this is safer and
easier to maintain.