Map \dx+ command to \dx, until PostgreSQL 9.1.
Map \dx+ command to \dx, until PostgreSQL 9.1.

The \dx+ command requires pg_describe_object() function, which we don't
have in GPDB yet. Until then, treat \dx+ the same as \dx.

Note that this code is written such that \dx+ can still be used, when
connected to a PostgreSQL 9.1 or later server. Not that we particularly care
about that case, but might as well.

Per github issue #2574.

Chibin/gpdb,jmcatamney/gpdb,kaknikhil/gpdb,ashwinstar/gpdb,Chibin/gpdb,janebeckman/gpdb,edespino/gpdb,cjcjameson/gpdb,50wu/gpdb,kaknikhil/gpdb,janebeckman/gpdb,edespino/gpdb,jmcatamney/gpdb,xinzweb/gpdb,janebeckman/gpdb,adam8157/gpdb,xinzweb/gpdb,xinzweb/gpdb,cjcjameson/gpdb,adam8157/gpdb,adam8157/gpdb,cjcjameson/gpdb,ashwinstar/gpdb,kaknikhil/gpdb,jmcatamney/gpdb,50wu/gpdb,kaknikhil/gpdb,janebeckman/gpdb,jmcatamney/gpdb,adam8157/gpdb,edespino/gpdb,Chibin/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,yuanzhao/gpdb,xinzweb/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,edespino/gpdb,yuanzhao/gpdb,xinzweb/gpdb,cjcjameson/gpdb,50wu/gpdb,lisakowen/gpdb,lisakowen/gpdb,yuanzhao/gpdb,lisakowen/gpdb,janebeckman/gpdb,greenplum-db/gpdb,lisakowen/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,Chibin/gpdb,kaknikhil/gpdb,lisakowen/gpdb,kaknikhil/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,ashwinstar/gpdb,adam8157/gpdb,lisakowen/gpdb,adam8157/gpdb,ashwinstar/gpdb,edespino/gpdb,yuanzhao/gpdb,cjcjameson/gpdb,Chibin/gpdb,janebeckman/gpdb,janebeckman/gpdb,Chibin/gpdb,janebeckman/gpdb,edespino/gpdb,xinzweb/gpdb,edespino/gpdb,50wu/gpdb,xinzweb/gpdb,lisakowen/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,Chibin/gpdb,adam8157/gpdb,janebeckman/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,50wu/gpdb,xinzweb/gpdb,lisakowen/gpdb,cjcjameson/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,cjcjameson/gpdb,kaknikhil/gpdb,50wu/gpdb,Chibin/gpdb,adam8157/gpdb,jmcatamney/gpdb,cjcjameson/gpdb,cjcjameson/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,Chibin/gpdb,kaknikhil/gpdb,50wu/gpdb,janebeckman/gpdb,edespino/gpdb,Chibin/gpdb,edespino/gpdb,greenplum-db/gpdb,cjcjameson/gpdb,greenplum-db/gpdb,50wu/gpdb,edespino/gpdb