Improve realloc() per idea from Karel Zak --- if chunk to be enlarged is at end of its block, maybe we can enlarge it in-place.
Improve realloc() per idea from Karel Zak --- if chunk to be enlarged is
at end of its block, maybe we can enlarge it in-place.

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