Fix generation of SP-GiST vacuum WAL records.
Fix generation of SP-GiST vacuum WAL records.

I broke these in 8776faa81cb651322b8993422bdd4633f1f6a487. Backpatch to
9.4, where that was done.

50wu/gpdb,xinzweb/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,xinzweb/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,xinzweb/gpdb,jmcatamney/gpdb,xinzweb/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,50wu/gpdb,xinzweb/gpdb,50wu/gpdb,adam8157/gpdb,xinzweb/gpdb,adam8157/gpdb,ashwinstar/gpdb,lisakowen/gpdb,jmcatamney/gpdb,50wu/gpdb,lisakowen/gpdb,jmcatamney/gpdb,adam8157/gpdb,adam8157/gpdb,lisakowen/gpdb,lisakowen/gpdb,50wu/gpdb,jmcatamney/gpdb,adam8157/gpdb,jmcatamney/gpdb,50wu/gpdb,greenplum-db/gpdb,50wu/gpdb,jmcatamney/gpdb,adam8157/gpdb,adam8157/gpdb,xinzweb/gpdb,lisakowen/gpdb,lisakowen/gpdb,ashwinstar/gpdb,lisakowen/gpdb,50wu/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,adam8157/gpdb,greenplum-db/gpdb,lisakowen/gpdb,ashwinstar/gpdb,xinzweb/gpdb,greenplum-db/gpdb