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.

Postgres-XL/Postgres-XL,jmcatamney/gpdb,snaga/postgres-xl,ashwinstar/gpdb,arcivanov/postgres-xl,greenplum-db/gpdb,kmjungersen/PostgresXL,50wu/gpdb,postmind-net/postgres-xl,50wu/gpdb,greenplum-db/gpdb,Postgres-XL/Postgres-XL,lisakowen/gpdb,adam8157/gpdb,kmjungersen/PostgresXL,arcivanov/postgres-xl,adam8157/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,zeroae/postgres-xl,techdragon/Postgres-XL,50wu/gpdb,50wu/gpdb,techdragon/Postgres-XL,greenplum-db/gpdb,yazun/postgres-xl,jmcatamney/gpdb,ovr/postgres-xl,techdragon/Postgres-XL,jmcatamney/gpdb,snaga/postgres-xl,greenplum-db/gpdb,greenplum-db/gpdb,yazun/postgres-xl,xinzweb/gpdb,lisakowen/gpdb,tpostgres-projects/tPostgres,pavanvd/postgres-xl,tpostgres-projects/tPostgres,lisakowen/gpdb,xinzweb/gpdb,snaga/postgres-xl,ashwinstar/gpdb,xinzweb/gpdb,ashwinstar/gpdb,adam8157/gpdb,pavanvd/postgres-xl,lisakowen/gpdb,adam8157/gpdb,ovr/postgres-xl,oberstet/postgres-xl,ovr/postgres-xl,oberstet/postgres-xl,oberstet/postgres-xl,yazun/postgres-xl,adam8157/gpdb,oberstet/postgres-xl,50wu/gpdb,adam8157/gpdb,xinzweb/gpdb,ashwinstar/gpdb,tpostgres-projects/tPostgres,50wu/gpdb,ovr/postgres-xl,zeroae/postgres-xl,jmcatamney/gpdb,snaga/postgres-xl,Postgres-XL/Postgres-XL,Postgres-XL/Postgres-XL,kmjungersen/PostgresXL,lisakowen/gpdb,greenplum-db/gpdb,lisakowen/gpdb,kmjungersen/PostgresXL,postmind-net/postgres-xl,jmcatamney/gpdb,oberstet/postgres-xl,jmcatamney/gpdb,xinzweb/gpdb,lisakowen/gpdb,tpostgres-projects/tPostgres,zeroae/postgres-xl,snaga/postgres-xl,arcivanov/postgres-xl,greenplum-db/gpdb,jmcatamney/gpdb,arcivanov/postgres-xl,adam8157/gpdb,lisakowen/gpdb,xinzweb/gpdb,Postgres-XL/Postgres-XL,zeroae/postgres-xl,50wu/gpdb,pavanvd/postgres-xl,ovr/postgres-xl,tpostgres-projects/tPostgres,techdragon/Postgres-XL,yazun/postgres-xl,zeroae/postgres-xl,postmind-net/postgres-xl,ashwinstar/gpdb,50wu/gpdb,arcivanov/postgres-xl,techdragon/Postgres-XL,greenplum-db/gpdb,arcivanov/postgres-xl,ashwinstar/gpdb,yazun/postgres-xl,pavanvd/postgres-xl,xinzweb/gpdb,kmjungersen/PostgresXL,xinzweb/gpdb,postmind-net/postgres-xl,postmind-net/postgres-xl,adam8157/gpdb,pavanvd/postgres-xl,ashwinstar/gpdb