Fix incorrect column name in psql \d code.
Fix incorrect column name in psql \d code.

pg_index.indisreplident had at one time in its development been called
indisidentity.  describe.c got missed when it was renamed.
Bug introduced in commit 07cacba983ef79be4a84fcd0e0ca3b5fcb85dd65.

Andres Freund

50wu/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,techdragon/Postgres-XL,greenplum-db/gpdb,yazun/postgres-xl,jmcatamney/gpdb,ovr/postgres-xl,ashwinstar/gpdb,lisakowen/gpdb,lisakowen/gpdb,xinzweb/gpdb,xinzweb/gpdb,adam8157/gpdb,lisakowen/gpdb,xinzweb/gpdb,ashwinstar/gpdb,pavanvd/postgres-xl,adam8157/gpdb,50wu/gpdb,ashwinstar/gpdb,pavanvd/postgres-xl,oberstet/postgres-xl,50wu/gpdb,techdragon/Postgres-XL,oberstet/postgres-xl,lisakowen/gpdb,techdragon/Postgres-XL,zeroae/postgres-xl,jmcatamney/gpdb,greenplum-db/gpdb,adam8157/gpdb,lisakowen/gpdb,adam8157/gpdb,oberstet/postgres-xl,zeroae/postgres-xl,lisakowen/gpdb,yazun/postgres-xl,xinzweb/gpdb,lisakowen/gpdb,jmcatamney/gpdb,yazun/postgres-xl,ashwinstar/gpdb,greenplum-db/gpdb,pavanvd/postgres-xl,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,xinzweb/gpdb,50wu/gpdb,ashwinstar/gpdb,50wu/gpdb,yazun/postgres-xl,ashwinstar/gpdb,Postgres-XL/Postgres-XL,ovr/postgres-xl,xinzweb/gpdb,ashwinstar/gpdb,ovr/postgres-xl,greenplum-db/gpdb,Postgres-XL/Postgres-XL,jmcatamney/gpdb,techdragon/Postgres-XL,zeroae/postgres-xl,zeroae/postgres-xl,greenplum-db/gpdb,Postgres-XL/Postgres-XL,adam8157/gpdb,ovr/postgres-xl,pavanvd/postgres-xl,ovr/postgres-xl,jmcatamney/gpdb,xinzweb/gpdb,Postgres-XL/Postgres-XL,oberstet/postgres-xl,pavanvd/postgres-xl,xinzweb/gpdb,adam8157/gpdb,techdragon/Postgres-XL,yazun/postgres-xl,greenplum-db/gpdb,jmcatamney/gpdb,50wu/gpdb,zeroae/postgres-xl,oberstet/postgres-xl,Postgres-XL/Postgres-XL,greenplum-db/gpdb,greenplum-db/gpdb,adam8157/gpdb,50wu/gpdb,jmcatamney/gpdb