This is no longer needed in 8.x, because all jobs moving from 6.x to
7.x will be forced to upgrade their rollup ID if they haven't already.
So by time we get to 8.x, all jobs will be on the new scheme.
This removes the old CRC generator and all the flags and state checking
to manage it. We do need to keep the serialization check since a mixed
cluster will have 7.x nodes sending/receiving the flag, so that is
just hardcoded until 9.0 when we can remove it.
29bca00604