Fix off-by-one error in autovacuum shmem struct sizing. This could lead to autovacuum worker sending SIGUSR1 signal to wrong process, per Zou Yong's report.
Fix off-by-one error in autovacuum shmem struct sizing. This could lead to
autovacuum worker sending SIGUSR1 signal to wrong process, per Zou Yong's
report.

Backpatch to 8.3.

Chibin/gpdb,greenplum-db/gpdb,xinzweb/gpdb,snaga/postgres-xl,Chibin/gpdb,xinzweb/gpdb,techdragon/Postgres-XL,adam8157/gpdb,lisakowen/gpdb,adam8157/gpdb,yuanzhao/gpdb,edespino/gpdb,arcivanov/postgres-xl,arcivanov/postgres-xl,ashwinstar/gpdb,techdragon/Postgres-XL,ashwinstar/gpdb,xinzweb/gpdb,Postgres-XL/Postgres-XL,50wu/gpdb,Postgres-XL/Postgres-XL,ashwinstar/gpdb,kmjungersen/PostgresXL,kmjungersen/PostgresXL,snaga/postgres-xl,greenplum-db/gpdb,lisakowen/gpdb,postmind-net/postgres-xl,zeroae/postgres-xl,adam8157/gpdb,ovr/postgres-xl,lisakowen/gpdb,edespino/gpdb,yuanzhao/gpdb,ovr/postgres-xl,ovr/postgres-xl,lisakowen/gpdb,edespino/gpdb,jmcatamney/gpdb,adam8157/gpdb,ashwinstar/gpdb,oberstet/postgres-xl,snaga/postgres-xl,ovr/postgres-xl,yazun/postgres-xl,arcivanov/postgres-xl,kmjungersen/PostgresXL,jmcatamney/gpdb,adam8157/gpdb,yuanzhao/gpdb,ovr/postgres-xl,Postgres-XL/Postgres-XL,oberstet/postgres-xl,tpostgres-projects/tPostgres,xinzweb/gpdb,oberstet/postgres-xl,Chibin/gpdb,greenplum-db/gpdb,Chibin/gpdb,ashwinstar/gpdb,edespino/gpdb,greenplum-db/gpdb,lisakowen/gpdb,zeroae/postgres-xl,jmcatamney/gpdb,zeroae/postgres-xl,yuanzhao/gpdb,yuanzhao/gpdb,edespino/gpdb,postmind-net/postgres-xl,Chibin/gpdb,Postgres-XL/Postgres-XL,yuanzhao/gpdb,xinzweb/gpdb,arcivanov/postgres-xl,lisakowen/gpdb,tpostgres-projects/tPostgres,greenplum-db/gpdb,greenplum-db/gpdb,edespino/gpdb,snaga/postgres-xl,jmcatamney/gpdb,Chibin/gpdb,yuanzhao/gpdb,50wu/gpdb,postmind-net/postgres-xl,jmcatamney/gpdb,greenplum-db/gpdb,50wu/gpdb,50wu/gpdb,Chibin/gpdb,kmjungersen/PostgresXL,yazun/postgres-xl,xinzweb/gpdb,lisakowen/gpdb,Postgres-XL/Postgres-XL,Chibin/gpdb,arcivanov/postgres-xl,jmcatamney/gpdb,adam8157/gpdb,edespino/gpdb,tpostgres-projects/tPostgres,ashwinstar/gpdb,jmcatamney/gpdb,Chibin/gpdb,postmind-net/postgres-xl,yuanzhao/gpdb,lisakowen/gpdb,pavanvd/postgres-xl,yazun/postgres-xl,adam8157/gpdb,50wu/gpdb,techdragon/Postgres-XL,snaga/postgres-xl,techdragon/Postgres-XL,jmcatamney/gpdb,kmjungersen/PostgresXL,greenplum-db/gpdb,50wu/gpdb,pavanvd/postgres-xl,postmind-net/postgres-xl,pavanvd/postgres-xl,tpostgres-projects/tPostgres,Chibin/gpdb,edespino/gpdb,zeroae/postgres-xl,xinzweb/gpdb,xinzweb/gpdb,yuanzhao/gpdb,edespino/gpdb,pavanvd/postgres-xl,yazun/postgres-xl,ashwinstar/gpdb,yazun/postgres-xl,yuanzhao/gpdb,ashwinstar/gpdb,arcivanov/postgres-xl,pavanvd/postgres-xl,oberstet/postgres-xl,edespino/gpdb,50wu/gpdb,50wu/gpdb,oberstet/postgres-xl,tpostgres-projects/tPostgres,zeroae/postgres-xl,adam8157/gpdb,techdragon/Postgres-XL