Hi,

I've finally created tests for tzset(3). They test the POSIX timezone 
string compliance.

This patch is intended to be applied after Brian's tzset changes have 
been pushed (see other discussion).

You can also find the test vectors online 
(https://github.com/jdoubleu/newlib-posix-tzset-tests/blob/main/timezones.h) 
and run the tests on linux with glibc 
(https://github.com/jdoubleu/newlib-posix-tzset-tests/tree/main/host_test).

Cheers
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🙎🏻‍♂️ jdoubleu