pgsql: Properly set relpersistence for fake relcache entries.

Properly set relpersistence for fake relcache entries.

This can result in buffers failing to be properly flushed at
checkpoint time, leading to data loss.

Report, diagnosis, and patch by Jeff Davis.

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/eb6e9b5ea4a5e733da705c053906f3aff47c9bf5

Modified Files
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src/backend/access/transam/xlogutils.c |    5 +++++
src/backend/storage/buffer/bufmgr.c    |    2 ++
2 files changed, 7 insertions(+), 0 deletions(-)