Add defenses against plpython functions being declared to take or return pseudotypes.  Not sure why I neglected to add these checks at the same time I added them to the other PLs, but it seems I did.
Add defenses against plpython functions being declared to take or return
pseudotypes.  Not sure why I neglected to add these checks at the same
time I added them to the other PLs, but it seems I did.

randomtask1155/gpdb,lpetrov-pivotal/gpdb,lintzc/gpdb,rubikloud/gpdb,randomtask1155/gpdb,cjcjameson/gpdb,lisakowen/gpdb,arcivanov/postgres-xl,jmcatamney/gpdb,tangp3/gpdb,tangp3/gpdb,arcivanov/postgres-xl,tpostgres-projects/tPostgres,edespino/gpdb,Quikling/gpdb,cjcjameson/gpdb,lisakowen/gpdb,lintzc/gpdb,50wu/gpdb,yuanzhao/gpdb,lisakowen/gpdb,greenplum-db/gpdb,50wu/gpdb,xuegang/gpdb,postmind-net/postgres-xl,ahachete/gpdb,royc1/gpdb,cjcjameson/gpdb,atris/gpdb,Chibin/gpdb,Postgres-XL/Postgres-XL,rvs/gpdb,rvs/gpdb,snaga/postgres-xl,50wu/gpdb,snaga/postgres-xl,kaknikhil/gpdb,postmind-net/postgres-xl,Quikling/gpdb,ahachete/gpdb,0x0FFF/gpdb,cjcjameson/gpdb,jmcatamney/gpdb,royc1/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,zeroae/postgres-xl,adam8157/gpdb,rvs/gpdb,cjcjameson/gpdb,rubikloud/gpdb,Chibin/gpdb,lintzc/gpdb,cjcjameson/gpdb,cjcjameson/gpdb,edespino/gpdb,kaknikhil/gpdb,edespino/gpdb,ashwinstar/gpdb,foyzur/gpdb,ashwinstar/gpdb,foyzur/gpdb,ahachete/gpdb,xuegang/gpdb,kmjungersen/PostgresXL,janebeckman/gpdb,rvs/gpdb,kaknikhil/gpdb,50wu/gpdb,tangp3/gpdb,greenplum-db/gpdb,atris/gpdb,lpetrov-pivotal/gpdb,arcivanov/postgres-xl,chrishajas/gpdb,atris/gpdb,CraigHarris/gpdb,ovr/postgres-xl,xuegang/gpdb,lisakowen/gpdb,Quikling/gpdb,janebeckman/gpdb,lpetrov-pivotal/gpdb,arcivanov/postgres-xl,xinzweb/gpdb,foyzur/gpdb,royc1/gpdb,lintzc/gpdb,xuegang/gpdb,lisakowen/gpdb,chrishajas/gpdb,lpetrov-pivotal/gpdb,oberstet/postgres-xl,jmcatamney/gpdb,greenplum-db/gpdb,tpostgres-projects/tPostgres,50wu/gpdb,randomtask1155/gpdb,postmind-net/postgres-xl,ovr/postgres-xl,atris/gpdb,zeroae/postgres-xl,zaksoup/gpdb,kaknikhil/gpdb,kmjungersen/PostgresXL,lintzc/gpdb,zaksoup/gpdb,ashwinstar/gpdb,atris/gpdb,Quikling/gpdb,janebeckman/gpdb,tangp3/gpdb,cjcjameson/gpdb,rvs/gpdb,janebeckman/gpdb,rubikloud/gpdb,xinzweb/gpdb,randomtask1155/gpdb,CraigHarris/gpdb,chrishajas/gpdb,randomtask1155/gpdb,tangp3/gpdb,ashwinstar/gpdb,adam8157/gpdb,techdragon/Postgres-XL,rubikloud/gpdb,edespino/gpdb,kaknikhil/gpdb,pavanvd/postgres-xl,tangp3/gpdb,xinzweb/gpdb,adam8157/gpdb,lpetrov-pivotal/gpdb,tpostgres-projects/tPostgres,ahachete/gpdb,zeroae/postgres-xl,postmind-net/postgres-xl,janebeckman/gpdb,snaga/postgres-xl,yuanzhao/gpdb,snaga/postgres-xl,pavanvd/postgres-xl,zaksoup/gpdb,CraigHarris/gpdb,techdragon/Postgres-XL,yuanzhao/gpdb,kaknikhil/gpdb,atris/gpdb,yuanzhao/gpdb,xuegang/gpdb,rubikloud/gpdb,postmind-net/postgres-xl,rvs/gpdb,Quikling/gpdb,yuanzhao/gpdb,Chibin/gpdb,greenplum-db/gpdb,ovr/postgres-xl,kaknikhil/gpdb,pavanvd/postgres-xl,CraigHarris/gpdb,jmcatamney/gpdb,50wu/gpdb,edespino/gpdb,ashwinstar/gpdb,0x0FFF/gpdb,Chibin/gpdb,yuanzhao/gpdb,CraigHarris/gpdb,foyzur/gpdb,oberstet/postgres-xl,xinzweb/gpdb,zaksoup/gpdb,arcivanov/postgres-xl,xinzweb/gpdb,zaksoup/gpdb,0x0FFF/gpdb,rubikloud/gpdb,greenplum-db/gpdb,cjcjameson/gpdb,xinzweb/gpdb,lisakowen/gpdb,Quikling/gpdb,lintzc/gpdb,kaknikhil/gpdb,Postgres-XL/Postgres-XL,lpetrov-pivotal/gpdb,oberstet/postgres-xl,ahachete/gpdb,rubikloud/gpdb,tangp3/gpdb,0x0FFF/gpdb,royc1/gpdb,techdragon/Postgres-XL,Chibin/gpdb,kmjungersen/PostgresXL,Chibin/gpdb,ashwinstar/gpdb,snaga/postgres-xl,adam8157/gpdb,xuegang/gpdb,ovr/postgres-xl,CraigHarris/gpdb,ahachete/gpdb,xuegang/gpdb,yuanzhao/gpdb,royc1/gpdb,Postgres-XL/Postgres-XL,CraigHarris/gpdb,Quikling/gpdb,yazun/postgres-xl,pavanvd/postgres-xl,jmcatamney/gpdb,atris/gpdb,foyzur/gpdb,arcivanov/postgres-xl,chrishajas/gpdb,Postgres-XL/Postgres-XL,edespino/gpdb,randomtask1155/gpdb,xuegang/gpdb,adam8157/gpdb,zaksoup/gpdb,jmcatamney/gpdb,rvs/gpdb,oberstet/postgres-xl,yazun/postgres-xl,0x0FFF/gpdb,Chibin/gpdb,randomtask1155/gpdb,tpostgres-projects/tPostgres,adam8157/gpdb,greenplum-db/gpdb,janebeckman/gpdb,adam8157/gpdb,cjcjameson/gpdb,lpetrov-pivotal/gpdb,xinzweb/gpdb,yuanzhao/gpdb,yazun/postgres-xl,rvs/gpdb,pavanvd/postgres-xl,rvs/gpdb,jmcatamney/gpdb,ahachete/gpdb,kmjungersen/PostgresXL,atris/gpdb,Chibin/gpdb,zaksoup/gpdb,edespino/gpdb,ovr/postgres-xl,edespino/gpdb,Quikling/gpdb,lintzc/gpdb,royc1/gpdb,royc1/gpdb,ashwinstar/gpdb,kmjungersen/PostgresXL,chrishajas/gpdb,royc1/gpdb,janebeckman/gpdb,foyzur/gpdb,lisakowen/gpdb,yazun/postgres-xl,edespino/gpdb,0x0FFF/gpdb,yuanzhao/gpdb,Chibin/gpdb,yuanzhao/gpdb,lisakowen/gpdb,zeroae/postgres-xl,greenplum-db/gpdb,rvs/gpdb,CraigHarris/gpdb,jmcatamney/gpdb,janebeckman/gpdb,ahachete/gpdb,rubikloud/gpdb,foyzur/gpdb,Quikling/gpdb,yazun/postgres-xl,zaksoup/gpdb,Chibin/gpdb,CraigHarris/gpdb,edespino/gpdb,janebeckman/gpdb,xinzweb/gpdb,lpetrov-pivotal/gpdb,chrishajas/gpdb,adam8157/gpdb,chrishajas/gpdb,0x0FFF/gpdb,lintzc/gpdb,tangp3/gpdb,Postgres-XL/Postgres-XL,foyzur/gpdb,xuegang/gpdb,janebeckman/gpdb,kaknikhil/gpdb,50wu/gpdb,techdragon/Postgres-XL,randomtask1155/gpdb,chrishajas/gpdb,techdragon/Postgres-XL,0x0FFF/gpdb,tpostgres-projects/tPostgres,Quikling/gpdb,oberstet/postgres-xl,zeroae/postgres-xl,lintzc/gpdb,50wu/gpdb,kaknikhil/gpdb