This change will be merged into 3.5 along with other encoding, command
line, environment variables, etc.

Revert following commits:

- bd831bcc
  [Bug #20929] Win32: Use `wcsftime`

- 1c15f641
  [Bug #20929] Win32: Encode timezone name in UTF-8

- 78762b52
  [Bug #20929] Fix `assert_zone_encoding`