[tz] proposed changes for Win32 and a improved mktime() algorithm

[Kees Dekker]

>Yes, and it's time to take the next step in deprecating yearistype, by 
>issuing warnings when people try to use it, rather than merely 
>documenting that it's deprecated. A proposed patch is attached.

>Also, due to this 2016-09-06 commit:

>https://github.com/eggert/tz/commit/6d70edaaf149e35ebb6d9107b216519debcc7f11

>zic now chdirs to its destination directory, which means 'zic -y 
>./yearistype' no longer works unless yearistype is in the destination 
>directory. I expect that nobody has reported the issue because nobody 
>uses yearistype any more.

Thanks.
Kees