pgsql: Need to reset local buffer pin counts, not only shared buffer

Log Message:
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Need to reset local buffer pin counts, not only shared buffer pins,
before we attempt any file deletions in ShutdownPostgres. Per Tatsuo.

Tags:
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REL8_0_STABLE

Modified Files:
--------------
pgsql/src/backend/storage/buffer:
localbuf.c (r1.62 -> r1.62.4.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/buffer/localbuf.c.diff?r1=1.62&r2=1.62.4.1)
pgsql/src/backend/utils/init:
postinit.c (r1.139.4.1 -> r1.139.4.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/init/postinit.c.diff?r1=1.139.4.1&r2=1.139.4.2)
pgsql/src/include/storage:
bufmgr.h (r1.89 -> r1.89.4.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/bufmgr.h.diff?r1=1.89&r2=1.89.4.1)