Output info in update.php for skipped updates due to shared tables

Can be kind of confusing for people to figure out why certain
updates didn't happen. I just had an irc conversation with
someone who didn't realize why their db wasn't fully updated.

Change-Id: I56223e70bdac8baaf079c28cbb1f0e20ef0336b8
Merge "Output info in update.php for skipped updates due to shared tables"