PATCH: pgbench - break out timing data for initialization phases

This patch is based against 'master'.

It adds collection of timing data for the initialization option phases and
reporting at the end of initialization.

Before patch:
.
.
.
199900000 of 200000000 tuples (99%) done (elapsed 158.96 s, remaining 0.08 s)
200000000 of 200000000 tuples (100%) done (elapsed 159.04 s, remaining 0.00 s)
vacuum...
set primary keys...
done.

After patch:
.
.
.
199900000 of 200000000 tuples (99%) done (elapsed 161.48 s, remaining 0.08 s)
200000000 of 200000000 tuples (100%) done (elapsed 161.56 s, remaining 0.00 s)
vacuum...
set primary keys...
total time: 316.03 s (insert 161.60 s, commit 0.64 s, vacuum 60.77 s, index 93.01 s)
done.

doug
--
Doug Rady
Amazon Aurora PostgreSQL
radydoug(at)amazon(dot)com