Temporarily revert stats collector latch changes so we can ship beta1.
Temporarily revert stats collector latch changes so we can ship beta1.

This patch reverts commit 49340037ee3ab46cb24144a86705e35f272c24d5 and some
follow-on tweaking in pgstat.c.  While the basic scheme of latch-ifying the
stats collector seems sound enough, it's failing on most Windows buildfarm
members for unknown reasons, and there's no time left to debug that before
9.2beta1.  Better to ship a beta version without this improvement.  I hope
to re-revert this once beta1 is out, though.

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