typedef long time_t;

There isn’t a lot of time before this evil, evil signed long value goes negative. It should make a good retirement gift for us; Kind of like the Y2K problem. Of course this issue goes away almost immediately when you start working on LP64 programming environments.
Grumbling about determining a particular time zone’s offset from UTC without actually setting the value. There doesn’t seem to be much in the lines of determining this without significant programmatic interference.