pgsql: Modify pg_test_fsync to match the behavior of git head in regard

Modify pg_test_fsync to match the behavior of git head in regards to
O_DIRECT behavior.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/303b7fcd10a34d8c8b4c3e6e258faeaf107dcf92

Modified Files
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contrib/pg_test_fsync/pg_test_fsync.c | 108 ++++++++------------------------
1 files changed, 27 insertions(+), 81 deletions(-)