pgsql: Backport patch.

Log Message:
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Backport patch.

Call srandom() instead of srand().
pgbench calls random() later, so it should have called srandom().
On most platforms except Windows srandom() is actually identical
to srand(), so the bug only bites Windows users.
per bug report from Akio Ishida.

Tags:
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REL8_2_STABLE

Modified Files:
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pgsql/contrib/pgbench:
pgbench.c (r1.58 -> r1.58.2.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pgbench/pgbench.c.diff?r1=1.58&r2=1.58.2.1)