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.

contrib/pgbench/pgbench.c

 /*
- * $PostgreSQL: pgsql/contrib/pgbench/pgbench.c,v 1.58 2006/10/21 06:31:28 ishii Exp $
+ * $PostgreSQL: pgsql/contrib/pgbench/pgbench.c,v 1.59 2006/12/26 01:02:05 ishii Exp $
  *
  * pgbench: a simple benchmark program for PostgreSQL
  * written by Tatsuo Ishii
@@ -1500,7 +1500,7 @@ main(int argc, char **argv)
 
 	/* set random seed */
 	gettimeofday(&tv1, NULL);
-	srand((unsigned int) tv1.tv_usec);
+	srandom((unsigned int) tv1.tv_usec);
 
 	/* get start up time */
 	gettimeofday(&tv1, NULL);