Re-enable edmCheckClassVersion for ROOT6

This ROOT6 specific pull request corrects the (non-framework) checksums for ROOT6 and re-enables edmCheckClassVersion.  The checksums in the framework were fixed in a previous pull request that is already merged.
Quite a few packages needed to have their classes_def.xml files resynched with the 7_4_X (ROOT5) branch before the changes for ROOT6 were applied.  The two most blatant examples are DataFormats/L1Trigger.and DataFormats/TrackReco.
Please merge this request as soon as convenient.