Fix lo_export usage in example programs.
Fix lo_export usage in example programs.

lo_export returns -1, not zero, on failure.

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