Fix STOP WAL LOCATION in backup history files no to return the next segment of XLOG_BACKUP_END record even if the the record is placed at a segment boundary. Furthermore the previous implementation could return nonexistent segment file name when the boundary is in segments that has "FE" suffix; We never use segments with "FF" suffix.
Fix STOP WAL LOCATION in backup history files no to return the next
segment of XLOG_BACKUP_END record even if the the record is placed
at a segment boundary. Furthermore the previous implementation could
return nonexistent segment file name when the boundary is in segments
that has "FE" suffix; We never use segments with "FF" suffix.

Backpatch to 8.0, where hot backup was introduced.

Reported by Fujii Masao.

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