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_1_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/fef2c17807e095a04441e4f1fe05f75d5578ead2

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(-)