pgsql: psql backward compatibility fix For servers older than 8.3, sort

Log Message:
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psql backward compatibility fix

For servers older than 8.3, sort display of child tables by relname instead
of oid::regclass::text, because the cast from regclass to text did not work
back then. The older display may be slightly worse when different schemas
are involved, but that should be rare enough.

Modified Files:
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pgsql/src/bin/psql:
describe.c (r1.222 -> r1.223)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/describe.c?r1=1.222&r2=1.223)