This allows Predecessor work with builtin msvcp140_atomic_wait.
The real information returned there should be not Windows time zones but instead IANA time zones. Windows probably gets that from icu.dll which we currently don't have.
Separately, __std_tzdb_get_leap_seconds() always returns NULL for me for some reason on Windows, even with the parameters the game is using (both locally and across Testbot), so the stub does the same.