pgsql: Fix oversight in my patch of yesterday: forgot to ensure that

Log Message:
-----------
Fix oversight in my patch of yesterday: forgot to ensure that stats would
still be forced out at backend exit.

Modified Files:
--------------
pgsql/src/backend/postmaster:
pgstat.c (r1.154 -> r1.155)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/pgstat.c.diff?r1=1.154&r2=1.155)
pgsql/src/backend/tcop:
postgres.c (r1.532 -> r1.533)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/postgres.c.diff?r1=1.532&r2=1.533)
pgsql/src/include:
pgstat.h (r1.57 -> r1.58)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/pgstat.h.diff?r1=1.57&r2=1.58)