LP#1394356 Patron purge circs retain post code

When purging a patron, clear the address data after circulation
anonymization to ensure the usr_post_code is retained.

Signed-off-by: Bill Erickson <berickxx@gmail.com>
Signed-off-by: Ben Shum <bshum@biblio.org>
LP#1394356: Stamping upgrade script for patron purge post code fix

Signed-off-by: Ben Shum <bshum@biblio.org>