Remove some dead code and obsolete, misleading comments.
Remove some dead code and obsolete, misleading comments.

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