[tz] Direct implementation of mktime_z

[Guy Harris]

On Sep 24, 2022, at 12:50 AM, Ted Phelps via tz <tz at iana.org> wrote:

> I was trying to distinguish between the "binary search the time_t range" approach, which is arguably an indirect way to perform the calculation, to an approach where the time_t is calculated with a bunch of algebra and whatnot.

Presumably the "algebra and whatnot" has a lot of coefficients based either on the contents of the tzif file or on some representation of the Zone and Rule entries in the source file - it's not something that can be calculated from a simple formula, as, if a simple formula sufficed, the tzdb data and code would be vastly simpler.