Fix ANALYZE to accumulate some minimal statistics for an all-null column. Per gripes from Mike Mascari and Bernd Heller.
Fix ANALYZE to accumulate some minimal statistics for an all-null column.
Per gripes from Mike Mascari and Bernd Heller.

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