pgsql: Minor patch on pgbench 1.

Log Message:
-----------
Minor patch on pgbench

1. -i option should run vacuum analyze only on pgbench tables, not *all*
tables in database.

2. pre-run cleanup step was DELETE FROM HISTORY then VACUUM HISTORY.
This is just a slow version of TRUNCATE HISTORY.

Simon Riggs

Modified Files:
--------------
    pgsql/contrib/pgbench:
        pgbench.c (r1.80 -> r1.81)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/pgbench/pgbench.c?r1=1.80&r2=1.81)
    pgsql/src/backend/utils/adt:
        formatting.c (r1.145 -> r1.146)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/formatting.c?r1=1.145&r2=1.146)