Log Message:
-----------
Properly access a buffer's LSN using existing access macros instead of abusing
knowledge of page layout.
Stolen from Jonah Harris' CRC patch
Modified Files:
--------------
pgsql/src/backend/storage/buffer:
bufmgr.c (r1.238 -> r1.239)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/buffer/bufmgr.c?r1=1.238&r2=1.239)