Log Message:
-----------
Add comment about checkpoint panic behavior during shutdown, per
suggestion from Qingqing Zhou.
Modified Files:
--------------
pgsql/src/backend/access/transam:
xlog.c (r1.187 -> r1.188)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c.diff?r1=1.187&r2=1.188)