Notes on fdatasync for the test suite

[Martin Pool]

> The last line is weird as the time stamp appears to be *after* the
> selftest start (22h36 >> 21:10) and I have no good guess here. I'd be
> inclined to guess for UTC+2 (so 22h36 UTC+2 == 20h36 UTC) but that would
> mean that even for that last submission, it took ~45 minutes to do
> whatever is needed before starting the 'make check', compile extensions
> and generate the doc ? A bit too much...
>
> Anyone knows how/when the file time stamp is created and in which TZ ?

file times will normally be updated every time data is written to them
(so, the last time anything was written) and they're stored in utc and
displayed as whatever tz you ask for.  It's possible but probably
unlikely a machine's clock is set wrong.

m