Fix ginint4_queryextract() to actually do what it was intended to do for an unsatisfiable query, such as indexcol && empty_array.  It should return -1 to tell GIN no scan is required; but silly typo disabled the logic for that, resulting in unnecessary "GIN indexes do not support whole-index scans" error. Per bug report from Jeff Trout.
Fix ginint4_queryextract() to actually do what it was intended to do for an
unsatisfiable query, such as indexcol && empty_array.  It should return -1
to tell GIN no scan is required; but silly typo disabled the logic for that,
resulting in unnecessary "GIN indexes do not support whole-index scans" error.
Per bug report from Jeff Trout.

Back-patch to 8.3 where the logic was introduced.

edespino/gpdb,rvs/gpdb,xinzweb/gpdb,rvs/gpdb,50wu/gpdb,lisakowen/gpdb,50wu/gpdb,janebeckman/gpdb,edespino/gpdb,ahachete/gpdb,kaknikhil/gpdb,0x0FFF/gpdb,xuegang/gpdb,greenplum-db/gpdb,Chibin/gpdb,kaknikhil/gpdb,rvs/gpdb,janebeckman/gpdb,edespino/gpdb,adam8157/gpdb,jmcatamney/gpdb,adam8157/gpdb,lisakowen/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,50wu/gpdb,rvs/gpdb,janebeckman/gpdb,xinzweb/gpdb,chrishajas/gpdb,greenplum-db/gpdb,ahachete/gpdb,royc1/gpdb,0x0FFF/gpdb,greenplum-db/gpdb,cjcjameson/gpdb,jmcatamney/gpdb,janebeckman/gpdb,xinzweb/gpdb,Quikling/gpdb,cjcjameson/gpdb,lisakowen/gpdb,kaknikhil/gpdb,yuanzhao/gpdb,zaksoup/gpdb,rvs/gpdb,yuanzhao/gpdb,chrishajas/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,lisakowen/gpdb,chrishajas/gpdb,0x0FFF/gpdb,cjcjameson/gpdb,rvs/gpdb,cjcjameson/gpdb,adam8157/gpdb,Quikling/gpdb,lintzc/gpdb,kaknikhil/gpdb,Quikling/gpdb,0x0FFF/gpdb,xuegang/gpdb,royc1/gpdb,CraigHarris/gpdb,royc1/gpdb,Quikling/gpdb,xuegang/gpdb,royc1/gpdb,zaksoup/gpdb,yuanzhao/gpdb,Chibin/gpdb,adam8157/gpdb,ahachete/gpdb,CraigHarris/gpdb,Quikling/gpdb,lintzc/gpdb,ahachete/gpdb,greenplum-db/gpdb,zaksoup/gpdb,edespino/gpdb,Chibin/gpdb,yuanzhao/gpdb,rvs/gpdb,Quikling/gpdb,adam8157/gpdb,ahachete/gpdb,lintzc/gpdb,janebeckman/gpdb,royc1/gpdb,xuegang/gpdb,ashwinstar/gpdb,lisakowen/gpdb,edespino/gpdb,50wu/gpdb,lintzc/gpdb,greenplum-db/gpdb,Quikling/gpdb,Quikling/gpdb,zaksoup/gpdb,ashwinstar/gpdb,cjcjameson/gpdb,CraigHarris/gpdb,jmcatamney/gpdb,royc1/gpdb,0x0FFF/gpdb,0x0FFF/gpdb,chrishajas/gpdb,rvs/gpdb,cjcjameson/gpdb,rvs/gpdb,janebeckman/gpdb,CraigHarris/gpdb,CraigHarris/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,CraigHarris/gpdb,kaknikhil/gpdb,edespino/gpdb,50wu/gpdb,ahachete/gpdb,kaknikhil/gpdb,CraigHarris/gpdb,xinzweb/gpdb,zaksoup/gpdb,ashwinstar/gpdb,50wu/gpdb,greenplum-db/gpdb,Quikling/gpdb,lintzc/gpdb,zaksoup/gpdb,50wu/gpdb,edespino/gpdb,xuegang/gpdb,adam8157/gpdb,Chibin/gpdb,yuanzhao/gpdb,Chibin/gpdb,zaksoup/gpdb,CraigHarris/gpdb,xinzweb/gpdb,xuegang/gpdb,0x0FFF/gpdb,ashwinstar/gpdb,lisakowen/gpdb,ahachete/gpdb,xinzweb/gpdb,xuegang/gpdb,chrishajas/gpdb,janebeckman/gpdb,xinzweb/gpdb,edespino/gpdb,edespino/gpdb,adam8157/gpdb,cjcjameson/gpdb,0x0FFF/gpdb,jmcatamney/gpdb,ahachete/gpdb,Chibin/gpdb,chrishajas/gpdb,yuanzhao/gpdb,cjcjameson/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,rvs/gpdb,janebeckman/gpdb,xinzweb/gpdb,chrishajas/gpdb,CraigHarris/gpdb,chrishajas/gpdb,yuanzhao/gpdb,zaksoup/gpdb,ashwinstar/gpdb,kaknikhil/gpdb,cjcjameson/gpdb,Chibin/gpdb,lisakowen/gpdb,kaknikhil/gpdb,lintzc/gpdb,royc1/gpdb,Chibin/gpdb,xuegang/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,lintzc/gpdb,Chibin/gpdb,lintzc/gpdb,kaknikhil/gpdb,edespino/gpdb,janebeckman/gpdb,Chibin/gpdb,lintzc/gpdb,Quikling/gpdb,kaknikhil/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,cjcjameson/gpdb,janebeckman/gpdb,xuegang/gpdb,royc1/gpdb,greenplum-db/gpdb