Remove 4th element of sigaction structure so it works on more platforms.
Remove 4th element of sigaction structure so it works on more platforms.

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