[libs][TimeZoneInfo] Bound transition time conversion (#21686)

Co-authored-by: mdh1418 <mitchhwang1418@gmail.com>

Author: github-actions[bot]

mcs/class/corlib/System/TimeZoneInfo.cs

@@ -1553,11 +1553,10 @@ static List<KeyValuePair<DateTime, TimeType>> ParseTransitions (byte [] buffer,
 return list;
 }
 
-static DateTime DateTimeFromUnixTime (long unix_time)
-{
-DateTime date_time = new DateTime (1970, 1, 1);
-return date_time.AddSeconds (unix_time);
-}
+static DateTime DateTimeFromUnixTime (long unix_time) =>
+unix_time < DateTimeOffset.UnixMinSeconds ? DateTime.MinValue :
+unix_time > DateTimeOffset.UnixMaxSeconds ? DateTime.MaxValue :
+DateTimeOffset.FromUnixTimeSeconds(unix_time).UtcDateTime;
 
 #region reference sources
 // Shortcut for TimeZoneInfo.Local.GetUtcOffset