pgsql: Dept.

Log Message:
-----------
Dept. of second thoughts: fix loop in BgBufferSync so that the exit when
bgwriter_lru_maxpages is exceeded leaves the loop variables in the
expected state.  In the original coding, we'd fail to advance
next_to_clean, causing that buffer to be probably-uselessly rechecked next
time, and also have an off-by-one idea of the number of buffers scanned.

Modified Files:
--------------
    pgsql/src/backend/storage/buffer:
        bufmgr.c (r1.225 -> r1.226)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/buffer/bufmgr.c?r1=1.225&r2=1.226)