pgsql: Fix WAL-logging of setting the visibility map bit.

Fix WAL-logging of setting the visibility map bit.

The operation that removes the remaining dead tuples from the page must
be WAL-logged before the setting of the VM bit. Otherwise, if you replay
the WAL to between those two records, you end up with the VM bit set, but
the dead tuples are still there.

Backpatch to 9.3, where this bug was introduced.

Branch
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REL9_3_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/615299cf63a730f9e170532c4782cd5a4a06a7ac

Modified Files
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src/backend/commands/vacuumlazy.c |   27 ++++++++++++---------------
1 file changed, 12 insertions(+), 15 deletions(-)