Fix case where the primary and backup dbds would both be performing rollup.

If the backup dbd happened to be doing rollup at the time the primary resumed
both the primary and the backup would be doing rollups and causing contention on
the database tables. The backup would wait for the rollup handler to finish
before giving up control.

The fix is to cancel the rollup_handler and let the backup begin to shutdown so
that it will close an existing connections and then re-exec itself. The re-exec
helps because the rollup handler spawns a thread for each cluster to rollup and
just cancelling the rollup handler doesn't cancel the spawned threads from the
rollup handler. This cleans up the dbd and locks. The re-exec only happens in
the backup if the primary resumed and a rollup was happening.

Bug 1988