Remove hash_destroy calls in hash_create's failure paths.  As noted by a Coverity warning, these are risky since the hashtable isn't necessarily fully set up yet.  They're unnecessary anyway: a deletable hashtable should be in a memory context that will be cleared following elog(ERROR). Per report from Martijn van Oosterhout.
Remove hash_destroy calls in hash_create's failure paths.  As noted by
a Coverity warning, these are risky since the hashtable isn't necessarily
fully set up yet.  They're unnecessary anyway: a deletable hashtable
should be in a memory context that will be cleared following elog(ERROR).
Per report from Martijn van Oosterhout.

ashwinstar/gpdb,postmind-net/postgres-xl,rubikloud/gpdb,lpetrov-pivotal/gpdb,lintzc/gpdb,janebeckman/gpdb,randomtask1155/gpdb,postmind-net/postgres-xl,chrishajas/gpdb,kmjungersen/PostgresXL,50wu/gpdb,ahachete/gpdb,0x0FFF/gpdb,chrishajas/gpdb,ashwinstar/gpdb,ahachete/gpdb,ahachete/gpdb,arcivanov/postgres-xl,greenplum-db/gpdb,xuegang/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,edespino/gpdb,Chibin/gpdb,ovr/postgres-xl,rvs/gpdb,yuanzhao/gpdb,Chibin/gpdb,randomtask1155/gpdb,postmind-net/postgres-xl,rvs/gpdb,zaksoup/gpdb,Chibin/gpdb,Quikling/gpdb,foyzur/gpdb,lpetrov-pivotal/gpdb,atris/gpdb,tpostgres-projects/tPostgres,rubikloud/gpdb,xinzweb/gpdb,kaknikhil/gpdb,jmcatamney/gpdb,rubikloud/gpdb,xinzweb/gpdb,xinzweb/gpdb,Chibin/gpdb,ahachete/gpdb,oberstet/postgres-xl,CraigHarris/gpdb,50wu/gpdb,CraigHarris/gpdb,cjcjameson/gpdb,greenplum-db/gpdb,oberstet/postgres-xl,foyzur/gpdb,jmcatamney/gpdb,janebeckman/gpdb,zaksoup/gpdb,lintzc/gpdb,edespino/gpdb,chrishajas/gpdb,snaga/postgres-xl,randomtask1155/gpdb,edespino/gpdb,ashwinstar/gpdb,Chibin/gpdb,xinzweb/gpdb,50wu/gpdb,atris/gpdb,arcivanov/postgres-xl,edespino/gpdb,jmcatamney/gpdb,Quikling/gpdb,50wu/gpdb,tpostgres-projects/tPostgres,oberstet/postgres-xl,yazun/postgres-xl,xuegang/gpdb,Postgres-XL/Postgres-XL,yazun/postgres-xl,pavanvd/postgres-xl,tangp3/gpdb,greenplum-db/gpdb,50wu/gpdb,CraigHarris/gpdb,lpetrov-pivotal/gpdb,kaknikhil/gpdb,greenplum-db/gpdb,0x0FFF/gpdb,royc1/gpdb,ahachete/gpdb,jmcatamney/gpdb,adam8157/gpdb,snaga/postgres-xl,xinzweb/gpdb,lisakowen/gpdb,yazun/postgres-xl,lpetrov-pivotal/gpdb,Chibin/gpdb,xuegang/gpdb,lintzc/gpdb,cjcjameson/gpdb,rvs/gpdb,yuanzhao/gpdb,cjcjameson/gpdb,randomtask1155/gpdb,ashwinstar/gpdb,rubikloud/gpdb,kmjungersen/PostgresXL,zaksoup/gpdb,0x0FFF/gpdb,yazun/postgres-xl,ashwinstar/gpdb,atris/gpdb,CraigHarris/gpdb,rubikloud/gpdb,snaga/postgres-xl,chrishajas/gpdb,50wu/gpdb,Chibin/gpdb,pavanvd/postgres-xl,Quikling/gpdb,xinzweb/gpdb,foyzur/gpdb,lintzc/gpdb,greenplum-db/gpdb,edespino/gpdb,jmcatamney/gpdb,adam8157/gpdb,Quikling/gpdb,kaknikhil/gpdb,cjcjameson/gpdb,zaksoup/gpdb,cjcjameson/gpdb,CraigHarris/gpdb,Quikling/gpdb,ovr/postgres-xl,lintzc/gpdb,atris/gpdb,royc1/gpdb,zeroae/postgres-xl,50wu/gpdb,lpetrov-pivotal/gpdb,rvs/gpdb,foyzur/gpdb,snaga/postgres-xl,foyzur/gpdb,kaknikhil/gpdb,pavanvd/postgres-xl,atris/gpdb,cjcjameson/gpdb,janebeckman/gpdb,ovr/postgres-xl,janebeckman/gpdb,pavanvd/postgres-xl,tangp3/gpdb,janebeckman/gpdb,rvs/gpdb,tpostgres-projects/tPostgres,yuanzhao/gpdb,postmind-net/postgres-xl,lintzc/gpdb,yuanzhao/gpdb,xuegang/gpdb,adam8157/gpdb,yuanzhao/gpdb,zeroae/postgres-xl,yazun/postgres-xl,kmjungersen/PostgresXL,techdragon/Postgres-XL,Quikling/gpdb,lpetrov-pivotal/gpdb,chrishajas/gpdb,yuanzhao/gpdb,atris/gpdb,0x0FFF/gpdb,tangp3/gpdb,yuanzhao/gpdb,adam8157/gpdb,CraigHarris/gpdb,CraigHarris/gpdb,tangp3/gpdb,edespino/gpdb,techdragon/Postgres-XL,Quikling/gpdb,Postgres-XL/Postgres-XL,janebeckman/gpdb,royc1/gpdb,royc1/gpdb,CraigHarris/gpdb,lisakowen/gpdb,0x0FFF/gpdb,techdragon/Postgres-XL,snaga/postgres-xl,kaknikhil/gpdb,jmcatamney/gpdb,lpetrov-pivotal/gpdb,Quikling/gpdb,Postgres-XL/Postgres-XL,50wu/gpdb,rubikloud/gpdb,zaksoup/gpdb,janebeckman/gpdb,arcivanov/postgres-xl,lisakowen/gpdb,kaknikhil/gpdb,0x0FFF/gpdb,ashwinstar/gpdb,xinzweb/gpdb,jmcatamney/gpdb,edespino/gpdb,royc1/gpdb,atris/gpdb,lisakowen/gpdb,zeroae/postgres-xl,royc1/gpdb,Chibin/gpdb,kaknikhil/gpdb,edespino/gpdb,edespino/gpdb,greenplum-db/gpdb,tpostgres-projects/tPostgres,rubikloud/gpdb,rvs/gpdb,rvs/gpdb,randomtask1155/gpdb,kmjungersen/PostgresXL,randomtask1155/gpdb,pavanvd/postgres-xl,ahachete/gpdb,randomtask1155/gpdb,arcivanov/postgres-xl,kaknikhil/gpdb,techdragon/Postgres-XL,CraigHarris/gpdb,oberstet/postgres-xl,greenplum-db/gpdb,lintzc/gpdb,arcivanov/postgres-xl,lisakowen/gpdb,tangp3/gpdb,chrishajas/gpdb,ovr/postgres-xl,Postgres-XL/Postgres-XL,lintzc/gpdb,jmcatamney/gpdb,cjcjameson/gpdb,Postgres-XL/Postgres-XL,xuegang/gpdb,zaksoup/gpdb,tangp3/gpdb,postmind-net/postgres-xl,Quikling/gpdb,tpostgres-projects/tPostgres,foyzur/gpdb,rvs/gpdb,tangp3/gpdb,cjcjameson/gpdb,lisakowen/gpdb,yuanzhao/gpdb,zeroae/postgres-xl,0x0FFF/gpdb,xuegang/gpdb,Chibin/gpdb,zeroae/postgres-xl,lisakowen/gpdb,ashwinstar/gpdb,kmjungersen/PostgresXL,tangp3/gpdb,lintzc/gpdb,kaknikhil/gpdb,arcivanov/postgres-xl,kaknikhil/gpdb,ahachete/gpdb,ahachete/gpdb,royc1/gpdb,foyzur/gpdb,oberstet/postgres-xl,zaksoup/gpdb,rubikloud/gpdb,xuegang/gpdb,randomtask1155/gpdb,Quikling/gpdb,atris/gpdb,adam8157/gpdb,royc1/gpdb,adam8157/gpdb,xuegang/gpdb,xinzweb/gpdb,yuanzhao/gpdb,xuegang/gpdb,janebeckman/gpdb,rvs/gpdb,adam8157/gpdb,ovr/postgres-xl,chrishajas/gpdb,zaksoup/gpdb,cjcjameson/gpdb,adam8157/gpdb,techdragon/Postgres-XL,chrishajas/gpdb,janebeckman/gpdb,0x0FFF/gpdb,rvs/gpdb,janebeckman/gpdb,edespino/gpdb,Chibin/gpdb,cjcjameson/gpdb,lpetrov-pivotal/gpdb,greenplum-db/gpdb,lisakowen/gpdb,foyzur/gpdb