[tz] iana build failures on Windows

[Guy Harris]

On Apr 22, 2021, at 11:22 PM, Manuela Friedrich via tz <tz at iana.org> wrote:

> please find the tracing output attached.
> I have only kept the first 136 lines believing it provides enough information.

	...

> d:\devsrc\treasure_test\iana\zoneinfo\iana\Africa\Abidjan  -9223372036854775808 = NULL

Is zdump linked with the rest of the tz code, or is it only linked with the Visual Studio C library?

If it's only linked with the Visual Studio C library, so that the localtime() that zdump calls is the Visual Studio C library's localtime(), rather than the tz code's localtime(), then it Will Not Work for any time before January 1, 1970, 00:00:00 UTC - localtime() in the Visual Studio C library returns NULL for all such date/time values:

	https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/localtime-localtime32-localtime64?view=msvc-160