Document some more #ifdef's
Document some more #ifdef's

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