Fix crash when pg_get_viewdef_name_ext() is passed a non-view relation.
Fix crash when pg_get_viewdef_name_ext() is passed a non-view relation.

Oversight in commit 976b24fb4.

Andreas Seltenreich

Report: <1ec4c0f898eae45ea384b12f5f8446eb73a298b3@credativ.de>

adam8157/gpdb,lisakowen/gpdb,jmcatamney/gpdb,50wu/gpdb,50wu/gpdb,adam8157/gpdb,ashwinstar/gpdb,50wu/gpdb,adam8157/gpdb,adam8157/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,adam8157/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,xinzweb/gpdb,50wu/gpdb,50wu/gpdb,lisakowen/gpdb,lisakowen/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,xinzweb/gpdb,jmcatamney/gpdb,lisakowen/gpdb,lisakowen/gpdb,lisakowen/gpdb,adam8157/gpdb,xinzweb/gpdb,50wu/gpdb,50wu/gpdb,xinzweb/gpdb,50wu/gpdb,adam8157/gpdb,adam8157/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,xinzweb/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,lisakowen/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,xinzweb/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,xinzweb/gpdb,lisakowen/gpdb,greenplum-db/gpdb,xinzweb/gpdb,ashwinstar/gpdb