This function retrieves the local machine's timezone information.
If the t argument is not NULL, it represents a time_t value to get timezone
information for. If it is NULL, the current time is used.
The gmtoff argument will be pointed at the number of seconds from GMT,
same value as the GNU (struct tm).tm_gmtoff extension.
The isdst argument will be pointed at zero if in standard time, one if in
daylight savings time and negative one if unknown.
The tzabbrp argument will be pointed at the timezone abbreviation, like
PST, ADT, EST, etc..