Fix Xmax freeze conditions
Fix Xmax freeze conditions

I broke this in 0ac5ad5134; previously, freezing a tuple marked with an
IS_MULTI xmax was not necessary.

Per brokenness report from Jeff Janes.

adam8157/gpdb,adam8157/gpdb,Postgres-XL/Postgres-XL,greenplum-db/gpdb,greenplum-db/gpdb,oberstet/postgres-xl,greenplum-db/gpdb,oberstet/postgres-xl,ovr/postgres-xl,lisakowen/gpdb,ashwinstar/gpdb,50wu/gpdb,jmcatamney/gpdb,zeroae/postgres-xl,jmcatamney/gpdb,techdragon/Postgres-XL,ashwinstar/gpdb,ovr/postgres-xl,lisakowen/gpdb,yazun/postgres-xl,ashwinstar/gpdb,Postgres-XL/Postgres-XL,yazun/postgres-xl,yazun/postgres-xl,techdragon/Postgres-XL,xinzweb/gpdb,adam8157/gpdb,ovr/postgres-xl,adam8157/gpdb,50wu/gpdb,adam8157/gpdb,pavanvd/postgres-xl,greenplum-db/gpdb,adam8157/gpdb,jmcatamney/gpdb,50wu/gpdb,xinzweb/gpdb,50wu/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,pavanvd/postgres-xl,jmcatamney/gpdb,ovr/postgres-xl,zeroae/postgres-xl,adam8157/gpdb,50wu/gpdb,xinzweb/gpdb,xinzweb/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,Postgres-XL/Postgres-XL,lisakowen/gpdb,50wu/gpdb,techdragon/Postgres-XL,50wu/gpdb,Postgres-XL/Postgres-XL,xinzweb/gpdb,lisakowen/gpdb,lisakowen/gpdb,50wu/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,pavanvd/postgres-xl,greenplum-db/gpdb,pavanvd/postgres-xl,xinzweb/gpdb,yazun/postgres-xl,ovr/postgres-xl,greenplum-db/gpdb,adam8157/gpdb,lisakowen/gpdb,lisakowen/gpdb,techdragon/Postgres-XL,xinzweb/gpdb,zeroae/postgres-xl,pavanvd/postgres-xl,xinzweb/gpdb,ashwinstar/gpdb,yazun/postgres-xl,zeroae/postgres-xl,zeroae/postgres-xl,oberstet/postgres-xl,jmcatamney/gpdb,oberstet/postgres-xl,oberstet/postgres-xl,ashwinstar/gpdb,Postgres-XL/Postgres-XL,techdragon/Postgres-XL,lisakowen/gpdb