Convert System::DateTime to _timeb

struct _timeb {
    long time;              // 4 bytes
    unsigned short millitm; // 2 bytes
    short timezone;         // 2 bytes
    short dstflag;          // 2 bytes
};

DateTime dateTime = DateTime::UtcNow;
DateTime baseTime(1970, 1, 1, 0, 0, 0, DateTimeKind::Utc);
TimeSpan delta = dateTime - baseTime;

_timeb timestamp;
timestamp.time     = delta.TotalSeconds;
timestamp.millitm  = dateTime.Millisecond;
timestamp.dstflag  = TimeZoneInfo::Local->IsDaylightSavingTime(dateTime) ? 1 : 0;
timestamp.timezone = TimeZoneInfo::Local->BaseUtcOffset.TotalMinutes * -1;