pgsql: In the checkpoint written at the end of archive recovery, the WAL

Log Message:
-----------
In the checkpoint written at the end of archive recovery, the WAL page header
was incorrectly initialized with timeline ID 0. That rendered the WAL page
unrecoverable, making a subsequent archive recovery stop at that point.
ThisTimeLineID needs to be initialized before calling AdvanceXLInsertBuffer().

This fixes bug #5011 reported by James Bardin. Backpatch to 8.4, as the bug
was introduced by the changes to use of bgwriter for writing the
end-of-archive-recovery checkpoint. Patch by Tom Lane.

Modified Files:
--------------
    pgsql/src/backend/access/transam:
        xlog.c (r1.348 -> r1.349)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c?r1=1.348&r2=1.349)