Bad header rand_seed with time_based or loops with randrepeat=0 verify

Bad header rand_seed with time_based or loops with randrepeat=0 verify

Verify fails with "bad header rand_seed" when multiple iterations of
do_io() execute (time_based=1 or loops>0), with verify enabled
and randrepeat=0

The root cause is do_verify() resetting the verify seed back to the
job-init value, which works for verification of the first iteration of
do_io() but fails for subsequent iterations because the seed is left in
its post-do_io() state after the first do_verify(), which means
different rand values for the second iteration of do_io() yet the second
iteration of do_verify() will revert back again to the job-init seed
value.

The fix is to revert the verify seed for randrepeat=0 back to ts state
when do_io() last ran rather than to its job-init value. That will allow
do_verify() to use the correct seed for each iteration while still
retaining a per-iteration unique verify seed.

Link: https://github.com/axboe/fio/issues/1517#issuecomment-1430282533
Signed-off-by: Adam Horshack (horshack@live.com)