Fix alignment of GIN in-line posting lists stored in entry tuples.
Fix alignment of GIN in-line posting lists stored in entry tuples.

The Sparc machines in the buildfarm are crashing because of misaligned
access to posting lists stored in entry tuples.

I accidentally removed a critical SHORTALIGN() from ginFormTuple, as part
of the packed posting lists patch. Perhaps I thought it was unnecessary,
because the index_form_tuple() call above the SHORTALIGN already aligned
the size, missing the fact that the null-category byte makes it misaligned
again (I think the SHORTALIGN is indeed unnecessary if there's no null-
category byte, but let's just play it safe...)

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