this obsoletes id:20170510113910.28444-1-david@tethera.net This is a simplification of the previous version, rather than swapping function pointers, we swap scanner tables. Unforunately because of the reorganization, the interdiff is unhelpfully large. The series shrunk from 6 to 4 patches; that's partly a cheat as the old 2/6 is now part of 4/4.