Cleanups for int8: guard against null inputs in comparison operators (and some other places), fix rangechecks in int8 to int4 conversion (same problem we recently figured out in pg_atoi).
Cleanups for int8: guard against null inputs in comparison
operators (and some other places), fix rangechecks in int8 to int4
conversion (same problem we recently figured out in pg_atoi).

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