pgsql: After archive recovery, mark the last WAL segment from the parent

Log Message:
-----------
After archive recovery, mark the last WAL segment from the parent timeline
ready for archival. It was marked at the next checkpoint anyway, but
waiting for the next checkpoint is an unnecessary delay.

Fujii Masao

Modified Files:
--------------
    pgsql/src/backend/access/transam:
        xlog.c (r1.335 -> r1.336)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c?r1=1.335&r2=1.336)