LP#1176206: improve deadlock handling in 2.3-2.4-supplemental.sh

- make sure that it doesn't attempt to create more than one
  index at a time for a given table
- if deadlocks occur (because of a PostgreSQL bug whose fix
  isn't slated for release until after April 2013), find
  and recreate the affected indexes.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Dan Scott <dscott@laurentian.ca>