Creates a DateTime corresponding to the given Unix time t in UTC.
Unix time is the number of seconds that have elapsed since 1970-01-01 00:00:00 UTC.
This call can fail (returning null) if t represents a time outside of the
supported range of DateTime.
You should release the return value by calling g_date_time_unref when you are done with it.
| t |
the Unix time |
|
a new DateTime, or null |