Make LockDatabaseObject() AcceptInvalidationMessages().
Make LockDatabaseObject() AcceptInvalidationMessages().

This is appropriate for the same reasons we already do it in
LockSharedObject(): things might have changed while we were waiting
for the lock.  There doesn't seem to be a live bug here at the moment,
but that's mostly because it isn't currently used for very much.

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