Fix crash if an EXPLAIN statement is passed to gp_dump_query_oids()
Fix crash if an EXPLAIN statement is passed to gp_dump_query_oids()

I was alerted to this by a compiler warning, which this also fixes. Was
broken by the 8.3 merge.

kaknikhil/gpdb,rvs/gpdb,ashwinstar/gpdb,50wu/gpdb,ahachete/gpdb,zaksoup/gpdb,CraigHarris/gpdb,lintzc/gpdb,adam8157/gpdb,zaksoup/gpdb,janebeckman/gpdb,janebeckman/gpdb,cjcjameson/gpdb,lisakowen/gpdb,0x0FFF/gpdb,edespino/gpdb,ahachete/gpdb,ahachete/gpdb,edespino/gpdb,janebeckman/gpdb,edespino/gpdb,xuegang/gpdb,ashwinstar/gpdb,chrishajas/gpdb,xuegang/gpdb,lintzc/gpdb,lintzc/gpdb,janebeckman/gpdb,ashwinstar/gpdb,rvs/gpdb,chrishajas/gpdb,royc1/gpdb,0x0FFF/gpdb,ashwinstar/gpdb,Quikling/gpdb,janebeckman/gpdb,xinzweb/gpdb,kaknikhil/gpdb,lisakowen/gpdb,lisakowen/gpdb,xuegang/gpdb,jmcatamney/gpdb,lisakowen/gpdb,0x0FFF/gpdb,0x0FFF/gpdb,chrishajas/gpdb,Quikling/gpdb,CraigHarris/gpdb,royc1/gpdb,50wu/gpdb,zaksoup/gpdb,edespino/gpdb,zaksoup/gpdb,ahachete/gpdb,50wu/gpdb,xinzweb/gpdb,jmcatamney/gpdb,lintzc/gpdb,cjcjameson/gpdb,cjcjameson/gpdb,janebeckman/gpdb,adam8157/gpdb,50wu/gpdb,Chibin/gpdb,royc1/gpdb,kaknikhil/gpdb,jmcatamney/gpdb,chrishajas/gpdb,Quikling/gpdb,ashwinstar/gpdb,cjcjameson/gpdb,kaknikhil/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,0x0FFF/gpdb,chrishajas/gpdb,edespino/gpdb,ahachete/gpdb,xuegang/gpdb,edespino/gpdb,CraigHarris/gpdb,royc1/gpdb,rvs/gpdb,Chibin/gpdb,50wu/gpdb,jmcatamney/gpdb,lintzc/gpdb,yuanzhao/gpdb,lintzc/gpdb,adam8157/gpdb,Quikling/gpdb,kaknikhil/gpdb,adam8157/gpdb,adam8157/gpdb,yuanzhao/gpdb,adam8157/gpdb,xuegang/gpdb,greenplum-db/gpdb,xuegang/gpdb,Quikling/gpdb,ahachete/gpdb,adam8157/gpdb,kaknikhil/gpdb,zaksoup/gpdb,greenplum-db/gpdb,lintzc/gpdb,rvs/gpdb,lintzc/gpdb,kaknikhil/gpdb,rvs/gpdb,edespino/gpdb,janebeckman/gpdb,Chibin/gpdb,cjcjameson/gpdb,0x0FFF/gpdb,cjcjameson/gpdb,ahachete/gpdb,Chibin/gpdb,0x0FFF/gpdb,yuanzhao/gpdb,edespino/gpdb,CraigHarris/gpdb,50wu/gpdb,janebeckman/gpdb,CraigHarris/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,zaksoup/gpdb,chrishajas/gpdb,xinzweb/gpdb,Quikling/gpdb,CraigHarris/gpdb,greenplum-db/gpdb,royc1/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,yuanzhao/gpdb,xinzweb/gpdb,Chibin/gpdb,rvs/gpdb,50wu/gpdb,cjcjameson/gpdb,greenplum-db/gpdb,royc1/gpdb,royc1/gpdb,chrishajas/gpdb,0x0FFF/gpdb,xinzweb/gpdb,jmcatamney/gpdb,rvs/gpdb,Chibin/gpdb,zaksoup/gpdb,Quikling/gpdb,Chibin/gpdb,ahachete/gpdb,CraigHarris/gpdb,chrishajas/gpdb,Quikling/gpdb,Chibin/gpdb,xinzweb/gpdb,lisakowen/gpdb,kaknikhil/gpdb,cjcjameson/gpdb,edespino/gpdb,yuanzhao/gpdb,CraigHarris/gpdb,greenplum-db/gpdb,cjcjameson/gpdb,janebeckman/gpdb,lisakowen/gpdb,Chibin/gpdb,Quikling/gpdb,royc1/gpdb,edespino/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,lintzc/gpdb,xinzweb/gpdb,greenplum-db/gpdb,xuegang/gpdb,50wu/gpdb,xuegang/gpdb,yuanzhao/gpdb,lisakowen/gpdb,adam8157/gpdb,rvs/gpdb,kaknikhil/gpdb,zaksoup/gpdb,janebeckman/gpdb,rvs/gpdb,Quikling/gpdb,cjcjameson/gpdb,xuegang/gpdb,greenplum-db/gpdb,rvs/gpdb,lisakowen/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,xinzweb/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,CraigHarris/gpdb,Chibin/gpdb