pgsql: Proceed to look for the next timezone when matching a localized

Log Message:
-----------
Proceed to look for the next timezone when matching a localized
Windows timezone name where the information in the registry is
incomplete, instead of aborting.

This fixes cases when the registry information is incomplete for
a timezone that is alphabetically before the one that is in use.

Per report from Alexander Forschner

Modified Files:
--------------
    pgsql/src/timezone:
        pgtz.c (r1.68 -> r1.69)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/timezone/pgtz.c?r1=1.68&r2=1.69)