s4:torture:basic: eliminate potential for false failures in delayed_write_update1

s4:torture:basic: eliminate potential for false failures in delayed_write_update1

We want to test that the write did update the write time immediately.
We check this by getting the file info in a loop for a few seconds.
There are several result cases:

- the server updated the write time immediately - success
- the server updated the write time, but not immediately - failure
- the server did not update the write time - failure

The loop is only there to be able to discern between the two
failure cases. The check for success is whether the first
getinfo has reportet the updated write time.

The potential for false failures was the additional timing check.
So if the first fileinfo call just took too long (e.g. due to a
busy system), this was reported as failure.

This patch should eliminate interemittent autobuild failures.

Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>