[HACKERS] pgbench --progress-timestamp no longer works correctly

--progress-timestamp is supposed to make -P report a Unix Epoch time stamp, for easy correlation with the entries in other log files (like the postgres server log file using %n).  

But that broke in this commit:

The commit before that one changed pgbench to make it tolerate the change in clock, but it overlooked --progress-timestamp.

Cheers,

Jeff