Fix outfuncs.c to dump A_Const nodes representing NULLs correctly.  This has been broken since forever, but was not noticed because people seldom look at raw parse trees.  AFAIK, no impact on users except that debug_print_parse might fail; but patch it all the way back anyway.  Per report from Jeff Ross.
Fix outfuncs.c to dump A_Const nodes representing NULLs correctly.  This has
been broken since forever, but was not noticed because people seldom look
at raw parse trees.  AFAIK, no impact on users except that debug_print_parse
might fail; but patch it all the way back anyway.  Per report from Jeff Ross.

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