doc: Fix PDF build with FOP
doc: Fix PDF build with FOP

Because of a bug in the DocBook XSL FO style sheet, an xref to a
varlistentry whose term includes an indexterm fails to build.  One such
instance was introduced in commit
5086dfceba79ecd5d1eb28b8f4ed5221838ff3a6.  Fix by adding the upstream
bug fix to our customization layer.

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